Center for Information Technology Services

Cyber Security Alerts (For Non-Technical Users)US Cert

  • TA14-290A: SSL 3.0 Protocol Vulnerability and POODLE Attack
    Original release date: October 17, 2014 | Last revised: October 20, 2014

    Systems Affected

    All systems and applications utilizing the Secure Socket Layer (SSL) 3.0 with cipher-block chaining (CBC) mode ciphers may be vulnerable. However, the POODLE (Padding Oracle On Downgraded Legacy Encryption) attack demonstrates this vulnerability using web browsers and web servers, which is one of the most likely exploitation scenarios.

    Overview

    US-CERT is aware of a design vulnerability found in the way SSL 3.0 handles block cipher mode padding. The POODLE attack demonstrates how an attacker can exploit this vulnerability to decrypt and extract information from inside an encrypted transaction.

    Description

    The SSL 3.0 vulnerability stems from the way blocks of data are encrypted under a specific type of encryption algorithm within the SSL protocol. The POODLE attack takes advantage of the protocol version negotiation feature built into SSL/TLS to force the use of SSL 3.0 and then leverages this new vulnerability to decrypt select content within the SSL session. The decryption is done byte by byte and will generate a large number of connections between the client and server.

    While SSL 3.0 is an old encryption standard and has generally been replaced by Transport Layer Security (TLS) (which is not vulnerable in this way), most SSL/TLS implementations remain backwards compatible with SSL 3.0 to interoperate with legacy systems in the interest of a smooth user experience. Even if a client and server both support a version of TLS the SSL/TLS protocol suite allows for protocol version negotiation (being referred to as the “downgrade dance” in other reporting). The POODLE attack leverages the fact that when a secure connection attempt fails, servers will fall back to older protocols such as SSL 3.0. An attacker who can trigger a connection failure can then force the use of SSL 3.0 and attempt the new attack. [1]

    Two other conditions must be met to successfully execute the POODLE attack: 1) the attacker must be able to control portions of the client side of the SSL connection (varying the length of the input) and 2) the attacker must have visibility of the resulting ciphertext. The most common way to achieve these conditions would be to act as Man-in-the-Middle (MITM), requiring a whole separate form of attack to establish that level of access.

    These conditions make successful exploitation somewhat difficult. Environments that are already at above-average risk for MITM attacks (such as public WiFi) remove some of those challenges.

    Impact

    The POODLE attack can be used against any system or application that supports SSL 3.0 with CBC mode ciphers. This affects most current browsers and websites, but also includes any software that either references a vulnerable SSL/TLS library (e.g. OpenSSL) or implements the SSL/TLS protocol suite itself. By exploiting this vulnerability in a likely web-based scenario, an attacker can gain access to sensitive data passed within the encrypted web session, such as passwords, cookies and other authentication tokens that can then be used to gain more complete access to a website (impersonating that user, accessing database content, etc.).

    Solution

    There is currently no fix for the vulnerability SSL 3.0 itself, as the issue is fundamental to the protocol; however, disabling SSL 3.0 support in system/application configurations is the most viable solution currently available.

    Some of the same researchers that discovered the vulnerability also developed a fix for one of the prerequisite conditions; TLS_FALLBACK_SCSV is a protocol extension that prevents MITM attackers from being able to force a protocol downgrade. OpenSSL has added support for TLS_FALLBACK_SCSV to their latest versions and recommend the following upgrades: [2]

    • OpenSSL 1.0.1 users should upgrade to 1.0.1j.
    • OpenSSL 1.0.0 users should upgrade to 1.0.0o.
    • OpenSSL 0.9.8 users should upgrade to 0.9.8zc.

    Both clients and servers need to support TLS_FALLBACK_SCSV to prevent downgrade attacks.

    Other SSL 3.0 implementations are most likely also affected by POODLE. Contact your vendor for details. Additional vendor information may be available in the National Vulnerability Database (NVD) entry for CVE-2014-3566 [3] or in CERT Vulnerability Note VU#577193. [4]

    References

    Revision History

    • October 17, 2014 Initial Release
    • October 20, 2014 Added CERT Vulnerability Note VU#577193 to the Solution section

    This product is provided subject to this Notification and this Privacy & Use policy.


  • TA14-268A: GNU Bourne-Again Shell (Bash) ‘Shellshock’ Vulnerability (CVE-2014-6271, CVE-2014-7169, CVE-2014-7186, CVE-2014-7187, CVE-2014-6277 and CVE 2014-6278)
    Original release date: September 25, 2014 | Last revised: September 30, 2014

    Systems Affected

    • GNU Bash through 4.3.
    • Linux and Mac OS X systems, on which Bash is part of the base operating system.
    • Any BSD or UNIX system on which GNU Bash has been installed as an add-on.
    • Any UNIX-like operating system on which the /bin/sh interface is implemented as GNU Bash.

    Overview

    A critical vulnerability has been reported in the GNU Bourne-Again Shell (Bash), the common command-line shell used in many Linux/UNIX operating systems and Apple’s Mac OS X. The flaw could allow an attacker to remotely execute shell commands by attaching malicious code in environment variables used by the operating system [1]. The United States Department of Homeland Security (DHS) is releasing this Technical Alert to provide further information about the GNU Bash vulnerability.

    Description

    GNU Bash versions 1.14 through 4.3 contain a flaw that processes commands placed after function definitions in the added environment variable, allowing remote attackers to execute arbitrary code via a crafted environment which enables network-based exploitation. [2, 3]

    Critical instances where the vulnerability may be exposed include: [4, 5]

    • Apache HTTP Server using mod_cgi or mod_cgid scripts either written in bash, or spawn GNU Bash subshells, or on any system where the /bin/sh interface is implemented using GNU Bash.
    • Override or Bypass ForceCommand feature in OpenSSH sshd and limited protection for some Git and Subversion deployments used to restrict shells and allows arbitrary command execution capabilities. This data path is vulnerable on systems where the /bin/sh interface is implemented using GNU Bash.
    • Allow arbitrary commands to run on a DHCP client machine.

    Impact

    This vulnerability is classified by industry standards as “High” impact with CVSS Impact Subscore 10 and “Low” on complexity, which means it takes little skill to perform. This flaw allows attackers who can provide specially crafted environment variables containing arbitrary commands to execute on vulnerable systems. It is especially dangerous because of the prevalent use of the Bash shell and its ability to be called by an application in numerous ways.

    Solution

    Initial solutions for Shellshock do not completely resolve the vulnerability. It is advised to install existing patches and pay attention for updated patches to address CVE-2014-6271, CVE-2014-7169, CVE-2014-7186, CVE-2014-7187, CVE-2014-6277, and CVE-2014-6278. Red Hat has provided a support article [6] with updated information.

    Many UNIX-like operating systems, including Linux distributions and Apple Mac OS X include Bash and are likely to be affected. Contact your vendor for updated information. A list of vendors can be found in CERT Vulnerability Note VU#252743 [7].

    US-CERT recommends system administrators review the vendor patches and the NIST Vulnerability Summaries for CVE-2014-6271, CVE-2014-7169, CVE-2014-7186, CVE-2014-7187, CVE-2014-6277 and CVE-2014-6278 to mitigate damage caused by the exploit.

    References

    Revision History

    • September 25, 2014 - Initial Release
    • September 26, 2014 - Minor Revisions
    • September 30, 2014 - Update to include additional CVE information

    This product is provided subject to this Notification and this Privacy & Use policy.


  • TA14-212A: Backoff Point-of-Sale Malware
    Original release date: July 31, 2014 | Last revised: August 27, 2014

    Systems Affected

    Point-of-Sale Systems

     

    Overview

    This advisory was prepared in collaboration with the National Cybersecurity and Communications Integration Center (NCCIC), United States Secret Service (USSS), Financial Sector Information Sharing and Analysis Center (FS-ISAC), and Trustwave Spiderlabs, a trusted partner under contract with the USSS.  The purpose of this release is to provide relevant and actionable technical indicators for network defense against the PoS malware dubbed "Backoff" which has been discovered exploiting businesses' administrator accounts remotely and exfiltrating consumer payment data.

    Over the past year, the Secret Service has responded to network intrusions at numerous businesses throughout the United States that have been impacted by the “Backoff” malware. Seven PoS system providers/vendors have confirmed that they have had multiple clients affected. Reporting continues on additional compromised locations, involving private sector entities of all sizes, and the Secret Service currently estimates that over 1,000 U.S. businesses are affected.

    Recent investigations revealed that malicious actors are using publicly available tools to locate businesses that use remote desktop applications. Remote desktop solutions like Microsoft's Remote Desktop [1], Apple Remote Desktop [2], Chrome Remote Desktop [3], Splashtop 2 [4], and LogMeIn [5] offer the convenience and efficiency of connecting to a computer from a remote location. Once these applications are located, the suspects attempted to brute force the login feature of the remote desktop solution. After gaining access to what was often administrator or privileged access accounts, the suspects were then able to deploy the point-of-sale (PoS) malware and subsequently exfiltrate consumer payment data via an encrypted POST request.

    Organizations that believe they have been impacted should contact their local Secret Service field office and may contact the NCCIC for additional information.

    Description

    “Backoff” is a family of PoS malware and has been discovered recently. The malware family has been witnessed on at least three separate forensic investigations. Researchers have identified three primary variants to the “Backoff” malware including 1.4, 1.55 (“backoff”, “goo”, “MAY”, “net”), and 1.56 (“LAST”).

    These variations have been seen as far back as October 2013 and continue to operate as of July 2014. In total, the malware typically consists of the following four capabilities. An exception is the earliest witnessed variant (1.4) which does not include keylogging functionality. Additionally, 1.55 ‘net’ removed the explorer.exe injection component:

    • Scraping memory for track data
    • Logging keystrokes
    • Command & control (C2) communication
    • Injecting malicious stub into explorer.exe

    The malicious stub that is injected into explorer.exe is responsible for persistence in the event the malicious executable crashes or is forcefully stopped. The malware is responsible for scraping memory from running processes on the victim machine and searching for track data. Keylogging functionality is also present in most recent variants of “Backoff”. Additionally, the malware has a C2 component that is responsible for uploading discovered data, updating the malware, downloading/executing further malware, and uninstalling the malware.

    Variants

    Based on compiled timestamps and versioning information witnessed in the C2 HTTP POST requests, “Backoff” variants were analyzed over a seven month period. The five variants witnessed in the “Backoff” malware family have notable modifications, to include:

    1.55 “backoff”

    • Added Local.dat temporary storage for discovered track data
    • Added keylogging functionality
    • Added “gr” POST parameter to include variant name
    • Added ability to exfiltrate keylog data
    • Supports multiple exfiltration domains
    • Changed install path
    • Changed User-Agent

    1.55 “goo”

    • Attempts to remove prior version of malware
    • Uses 8.8.8.8 as resolver

    1.55 “MAY”

    • No significant updates other than changes to the URI and version name

    1.55 “net”

    • Removed the explorer.exe injection component

    1.56 “LAST”

    • Re-added the explorer.exe injection component
    • Support for multiple domain/URI/port configurations
    • Modified code responsible for creating exfiltration thread(s)
    • Added persistence techniques

    Command & Control Communication

    All C2 communication for “Backoff” takes place via HTTP POST requests. A number of POST parameters are included when this malware makes a request to the C&C server.

    • op : Static value of ‘1’
    • id : randomly generated 7 character string
    • ui : Victim username/hostname
    • wv : Version of Microsoft Windows
    • gr (Not seen in version 1.4) : Malware-specific identifier
    • bv : Malware version
    • data (optional) : Base64-encoded/RC4-encrypted data

    The ‘id’ parameter is stored in the following location, to ensure it is consistent across requests:

    • HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\identifier

    If this key doesn’t exist, the string will be generated and stored. Data is encrypted using RC4 prior to being encoded with Base64. The password for RC4 is generated from the ‘id’ parameter, a static string of ‘jhgtsd7fjmytkr’, and the ‘ui’ parameter. These values are concatenated together and then hashed using the MD5 algorithm to form the RC4 password. In the above example, the RC4 password would be ‘56E15A1B3CB7116CAB0268AC8A2CD943 (The MD5 hash of ‘vxeyHkSjhgtsd7fjmytkrJosh @ PC123456).

    File Indicators:

    The following is a list of the Indicators of Compromise (IOCs) that should be added to the network security to search to see if these indicators are on their network.

    1.4

    Packed MD5: 927AE15DBF549BD60EDCDEAFB49B829E

    Unpacked MD5: 6A0E49C5E332DF3AF78823CA4A655AE8

    Install Path: %APPDATA%\AdobeFlashPlayer\mswinsvc.exe

    Mutexes:

    uhYtntr56uisGst

    uyhnJmkuTgD

    Files Written:

    %APPDATA%\mskrnl

    %APPDATA%\winserv.exe

    %APPDATA%\AdobeFlashPlayer\mswinsvc.exe

    Static String (POST Request): zXqW9JdWLM4urgjRkX

    Registry Keys:

    HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\identifier

    HKCU\ SOFTWARE \Microsoft\Windows\CurrentVersion\Run\Windows NT Service

    User-Agent: Mozilla/4.0

    URI(s): /aircanada/dark.php

    1.55 “backoff”

    Packed MD5: F5B4786C28CCF43E569CB21A6122A97E

    Unpacked MD5: CA4D58C61D463F35576C58F25916F258

    Install Path: %APPDATA%\AdobeFlashPlayer\mswinhost.exe

    Mutexes:

    Undsa8301nskal

    uyhnJmkuTgD

    Files Written:

    %APPDATA%\mskrnl

    %APPDATA%\winserv.exe

    %APPDATA%\AdobeFlashPlayer\mswinhost.exe

    %APPDATA%\AdobeFlashPlayer\Local.dat

    %APPDATA%\AdobeFlashPlayer\Log.txt

    Static String (POST Request): ihasd3jasdhkas

    Registry Keys:

    HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\identifier

    HKCU\ SOFTWARE \Microsoft\Windows\CurrentVersion\Run\Windows NT Service

    User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Firefox/24.0

    URI(s): /aero2/fly.php

    1.55 “goo”

    Pa  cked MD5: 17E1173F6FC7E920405F8DBDE8C9ECAC

    Unpacked MD5: D397D2CC9DE41FB5B5D897D1E665C549

    Install Path: %APPDATA%\OracleJava\javaw.exe

    Mutexes:

    nUndsa8301nskal

    nuyhnJmkuTgD

    Files Written:

    %APPDATA%\nsskrnl

    %APPDATA%\winserv.exe

    %APPDATA%\OracleJava\javaw.exe

    %APPDATA%\OracleJava\Local.dat

    %APPDATA%\OracleJava\Log.txt

    Static String (POST Request): jhgtsd7fjmytkr

    Registry Keys:

    HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\identifier

    HKCU\ SOFTWARE \Microsoft\Windows\CurrentVersion\Run\Windows NT Service

    User-Agent:

    URI(s): /windows/updcheck.php

    1.55 “MAY”

    Packed MD5: 21E61EB9F5C1E1226F9D69CBFD1BF61B

    Unpacked MD5: CA608E7996DED0E5009DB6CC54E08749

    Install Path: %APPDATA%\OracleJava\javaw.exe

    Mutexes:

    nUndsa8301nskal

    nuyhnJmkuTgD

    Files Written:

    %APPDATA%\nsskrnl

    %APPDATA%\winserv.exe

    %APPDATA%\OracleJava\javaw.exe

    %APPDATA%\OracleJava\Local.dat

    %APPDATA%\OracleJava\Log.txt

    Static String (POST Request): jhgtsd7fjmytkr

    Registry Keys:

    HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\identifier

    HKCU\ SOFTWARE \Microsoft\Windows\CurrentVersion\Run\Windows NT Service

    User-Agent:

    URI(s): /windowsxp/updcheck.php

    1.55 “net”

    Packed MD5: 0607CE9793EEA0A42819957528D92B02

    Unpacked MD5: 5C1474EA275A05A2668B823D055858D9

    Install Path: %APPDATA%\AdobeFlashPlayer\mswinhost.exe

    Mutexes:

    nUndsa8301nskal

    Files Written:

    %APPDATA%\AdobeFlashPlayer\mswinhost.exe

    %APPDATA%\AdobeFlashPlayer\Local.dat

    %APPDATA%\AdobeFlashPlayer\Log.txt

    Static String (POST Request): ihasd3jasdhkas9

    Registry Keys:

    HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\identifier

    HKCU\ SOFTWARE \Microsoft\Windows\CurrentVersion\Run\Windows NT Service

    User-Agent:

    URI(s): /windowsxp/updcheck.php

    1.56 “LAST”

    Packed MD5: 12C9C0BC18FDF98189457A9D112EEBFC

    Unpacked MD5: 205947B57D41145B857DE18E43EFB794

    Install Path: %APPDATA%\OracleJava\javaw.exe

    Mutexes:

    nUndsa8301nskal

    nuyhnJmkuTgD

    Files Written:

    %APPDATA%\nsskrnl

    %APPDATA%\winserv.exe

    %APPDATA%\OracleJava\javaw.exe

    %APPDATA%\OracleJava\Local.dat

    %APPDATA%\OracleJava\Log.txt

    Static String (POST Request): jhgtsd7fjmytkr

    Registry Keys:

    HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\identifier

    HKCU\ SOFTWARE \Microsoft\Windows\CurrentVersion\Run\Windows NT Service

    HKLM\ SOFTWARE \Microsoft\Windows\CurrentVersion\Run\Windows NT Service

    HKCU\SOFTWARE\\Microsoft\Active Setup\Installed Components\{B3DB0D62-B481-4929-888B-49F426C1A136}\StubPath

    HKLM\SOFTWARE\\Microsoft\Active Setup\Installed Components\{B3DB0D62-B481-4929-888B-49F426C1A136}\StubPath

    User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Firefox/24.0

    URI(s):  /windebug/updcheck.php

    Impact

    The impact of a compromised PoS system can affect both the businesses and consumer by exposing customer data such as names, mailing addresses, credit/debit card numbers, phone numbers, and e-mail addresses to criminal elements. These breaches can impact a business’ brand and reputation, while consumers’ information can be used to make fraudulent purchases or risk compromise of bank accounts. It is critical to safeguard your corporate networks and web servers to prevent any unnecessary exposure to compromise or to mitigate any damage that could be occurring now.

    Solution

    At the time this advisory is released, the variants of the “Backoff’ malware family are largely undetected by anti-virus (AV) vendors. However, shortly following the publication of this technical analysis, AV companies will quickly begin detecting the existing variants. It’s important to maintain up‐to‐date AV signatures and engines as new threats such as this are continually being added to your AV solution. Pending AV detection of the malware variants, network defenders can apply indicators of compromise (IOC) to a variety of prevention and detection strategies.[6],[7],[8] IOCs can be found above.

    The forensic investigations of compromises of retail IT/payment networks indicate that the network compromises allowed the introduction of memory scraping malware to the payment terminals. Information security professionals recommend a defense in depth approach to mitigating risk to retail payment systems. While some of the risk mitigation recommendations are general in nature, the following strategies provide an approach to minimize the possibility of an attack and mitigate the risk of data compromise:

    Remote Desktop Access

    • Configure the account lockout settings to lock a user account after a period of time or a specified number of failed login attempts. This prevents unlimited unauthorized attempts to login whether from an unauthorized user or via automated attack types like brute force.[9]
    • Limit the number of users and workstation who can log in using Remote Desktop.
    • Use firewalls (both software and hardware where available) to restrict access to remote desktop listening ports (default is TCP 3389).[10]
    • Change the default Remote Desktop listening port.
    • Define complex password parameters. Configuring an expiration time and password length and complexity can decrease the amount of time in which a successful attack can occur.[11]
    • Require two-factor authentication (2FA) for remote desktop access.[12]
    • Install a Remote Desktop Gateway to restrict access.[13]
    • Add an extra layer of authentication and encryption by tunneling your Remote Desktop through IPSec, SSH or SSL.[14],[15]
    • Require 2FA when accessing payment processing networks. Even if a virtual private network is used, it is important that 2FA is implemented to help mitigate keylogger or credential dumping attacks.
    • Limit administrative privileges for users and applications.
    • Periodically review systems (local and domain controllers) for unknown and dormant users.

    Network Security

    • Review firewall configurations and ensure that only allowed ports, services and Internet protocol (IP) addresses are communicating with your network. This is especially critical for outbound (e.g., egress) firewall rules in which compromised entities allow ports to communicate to any IP address on the Internet. Hackers leverage this configuration to exfiltrate data to their IP addresses.
    • Segregate payment processing networks from other networks.
    • Apply access control lists (ACLs) on the router configuration to limit unauthorized traffic to payment processing networks.
    • Create strict ACLs segmenting public-facing systems and back-end database systems that house payment card data.
    • Implement data leakage prevention/detection tools to detect and help prevent data exfiltration.
    • Implement tools to detect anomalous network traffic and anomalous behavior by legitimate users (compromised credentials).

    Cash Register and PoS Security

    • Implement hardware-based point-to-point encryption. It is recommended that EMV-enabled PIN entry devices or other credit-only accepting devices have Secure Reading and Exchange of Data (SRED) capabilities. SRED-approved devices can be found at the Payment Card Industry Security Standards website.
    • Install Payment Application Data Security Standard-compliant payment applications.
    • Deploy the latest version of an operating system and ensure it is up to date with security patches, anti-virus software, file integrity monitoring and a host-based intrusion-detection system.
    • Assign a strong password to security solutions to prevent application modification. Use two-factor authentication (2FA) where feasible.
    • Perform a binary or checksum comparison to ensure unauthorized files are not installed.
    • Ensure any automatic updates from third parties are validated. This means performing a checksum comparison on the updates prior to deploying them on PoS systems. It is recommended that merchants work with their PoS vendors to obtain signatures and hash values to perform this checksum validation.
    • Disable unnecessary ports and services, null sessions, default users and guests.
    • Enable logging of events and make sure there is a process to monitor logs on a daily basis.
    • Implement least privileges and ACLs on users and applications on the system.

    References

    Revision History

    • July, 31 2014 - Initial Release
    • August 18, 2014 - Minor revision to remote desktop solutions list
    • August 22, 2014 - Changes to the Overview section
    • August 26, 2014 - Minor revision to remote desktop solutions list

    This product is provided subject to this Notification and this Privacy & Use policy.


  • TA14-150A: GameOver Zeus P2P Malware
    Original release date: June 02, 2014 | Last revised: August 18, 2014

    Systems Affected

    • Microsoft Windows 95, 98, Me, 2000, XP, Vista, 7, and 8
    • Microsoft Server 2003, Server 2008, Server 2008 R2, and Server 2012

    Overview

    GameOver Zeus (GOZ), a peer-to-peer (P2P) variant of the Zeus family of bank credential-stealing malware identified in September 2011, [1] uses a decentralized network infrastructure of compromised personal computers and web servers to execute command-and-control. The United States Department of Homeland Security (DHS), in collaboration with the Federal Bureau of Investigation (FBI) and the Department of Justice (DOJ), is releasing this Technical Alert to provide further information about the GameOver Zeus botnet.

    Description

    GOZ, which is often propagated through spam and phishing messages, is primarily used by cybercriminals to harvest banking information, such as login credentials, from a victim’s computer. [2] Infected systems can also be used to engage in other malicious activities, such as sending spam or participating in distributed denial-of-service (DDoS) attacks. 

    Prior variants of the Zeus malware utilized a centralized command and control (C2) botnet infrastructure to execute commands. Centralized C2 servers are routinely tracked and blocked by the security community. [1] GOZ, however, utilizes a P2P network of infected hosts to communicate and distribute data, and employs encryption to evade detection. These peers act as a massive proxy network that is used to propagate binary updates, distribute configuration files, and to send stolen data. [3] Without a single point of failure, the resiliency of GOZ’s P2P infrastructure makes takedown efforts more difficult. [1]

    Impact

    A system infected with GOZ may be employed to send spam, participate in DDoS attacks, and harvest users' credentials for online services, including banking services.

    Solution

    Users are recommended to take the following actions to remediate GOZ infections:

    • Use and maintain anti-virus software - Anti-virus software recognizes and protects your computer against most known viruses. It is important to keep your anti-virus software up-to-date (see Understanding Anti-Virus Software for more information).
    • Change your passwords - Your original passwords may have been compromised during the infection, so you should change them (see Choosing and Protecting Passwords for more information).
    • Keep your operating system and application software up-to-date - Install software patches so that attackers can't take advantage of known problems or vulnerabilities. Many operating systems offer automatic updates. If this option is available, you should enable it (see Understanding Patches for more information).
    • Use anti-malware tools - Using a legitimate program that identifies and removes malware can help eliminate an infection. Users can consider employing a remediation tool (examples below) that will help with the removal of GOZ from your system.

    F-Secure       

    http://www.f-secure.com/en/web/home_global/online-scanner (Windows Vista, 7 and 8)

    http://www.f-secure.com/en/web/labs_global/removal-tools/-/carousel/view/142 (Windows XP)

    Heimdal

    http://goz.heimdalsecurity.com/ (Microsoft Windows XP, Vista, 7, 8 and 8.1)   

    McAfee

    www.mcafee.com/stinger (Windows XP SP2, 2003 SP2, Vista SP1, 2008, 7 and 8)

    Microsoft

    http://www.microsoft.com/security/scanner/en-us/default.aspx (Windows 8.1, Windows 8, Windows 7, Windows Vista, and Windows XP) 

    Sophos

    http://www.sophos.com/VirusRemoval (Windows XP (SP2) and above) 

    Symantec

    http://www.symantec.com/connect/blogs/international-takedown-wounds-gameover-zeus-cybercrime-network (Windows XP, Windows Vista and Windows 7)

    Trend Micro

    http://www.trendmicro.com/threatdetector (Windows XP, Windows Vista, Windows 7, Windows 8/8.1, Windows Server 2003, Windows Server 2008, and Windows Server 2008 R2)

    FireEye and Fox-IT

    www.decryptcryptolocker.com FireEye and Fox-IT have created a web portal claiming to restore/decrypt files of CryptoLocker victims. US-CERT has performed no evaluation of this claim, but is providing a link to enable individuals to make their own determination of suitability for their needs. At present, US-CERT is not aware of any other product that claims similar functionality.

    The above are examples only and do not constitute an exhaustive list. The U.S. Government does not endorse or support any particular product or vendor.

     

    References

    Revision History

    • Initial Publication - June 2, 2014
    • Added McAfee - June 6, 2014
    • Added FireEye and Fox-IT web portal to Solutions section - August 15, 2014

    This product is provided subject to this Notification and this Privacy & Use policy.


  • TA14-098A: OpenSSL 'Heartbleed' vulnerability (CVE-2014-0160)
    Original release date: April 08, 2014

    Systems Affected

    • OpenSSL 1.0.1 through 1.0.1f
    • OpenSSL 1.0.2-beta

    Overview

    A vulnerability in OpenSSL could allow a remote attacker to expose sensitive data, possibly including user authentication credentials and secret keys, through incorrect memory handling in the TLS heartbeat extension.

    Description

    OpenSSL versions 1.0.1 through 1.0.1f contain a flaw in its implementation of the TLS/DTLS heartbeat functionality. This flaw allows an attacker to retrieve private memory of an application that uses the vulnerable OpenSSL library in chunks of 64k at a time. Note that an attacker can repeatedly leverage the vulnerability to retrieve as many 64k chunks of memory as are necessary to retrieve the intended secrets. The sensitive information that may be retrieved using this vulnerability include:

    • Primary key material (secret keys)
    • Secondary key material (user names and passwords used by vulnerable services)
    • Protected content (sensitive data used by vulnerable services)
    • Collateral (memory addresses and content that can be leveraged to bypass exploit mitigations)

    Exploit code is publicly available for this vulnerability.  Additional details may be found in CERT/CC Vulnerability Note VU#720951.

    Impact

    This flaw allows a remote attacker to retrieve private memory of an application that uses the vulnerable OpenSSL library in chunks of 64k at a time.

    Solution

    OpenSSL 1.0.1g has been released to address this vulnerability.  Any keys generated with a vulnerable version of OpenSSL should be considered compromised and regenerated and deployed after the patch has been applied.

    US-CERT recommends system administrators consider implementing Perfect Forward Secrecy to mitigate the damage that may be caused by future private key disclosures.

    References

    Revision History

    • Initial Publication

    This product is provided subject to this Notification and this Privacy & Use policy.


  • TA14-069A: Microsoft Ending Support for Windows XP and Office 2003
    Original release date: March 10, 2014 | Last revised: June 18, 2014

    Systems Affected

    • Microsoft Windows XP with Service Pack 3 (SP3) Operating System
    • Microsoft Office 2003 Products

    Overview

    Microsoft is ending support for the Windows XP operating system and Office 2003 product line on April 8, 2014. [1] After this date, these products will no longer receive:

    • Security patches which help protect PCs from harmful viruses, spyware, and other malicious software
    • Assisted technical support from Microsoft
    • Software and content updates

    Description

    All software products have a lifecycle. End of support refers to the date when Microsoft no longer provides automatic fixes, updates, or online technical assistance. [2] As of February 2014, nearly 30 percent of Internet-connected PCs still run Windows XP. [3]

    Microsoft will send “End of Support” notifications to users of Windows XP who have elected to receive updates via Windows Update. Users in organizations using Windows Server Update Services (WSUS), System Center Configuration manager, or Windows Intune will not receive the notification. [4]

    Impact

    Computer systems running unsupported software are exposed to an elevated risk to cybersecurity dangers, such as malicious attacks or electronic data loss.

    Users may also encounter problems with software and hardware compatibility since new software applications and hardware devices may not be built for Windows XP or Office 2003.

    Organizations that are governed by regulatory obligations may find they are no longer able to satisfy compliance requirements. [4]

    Solution

    Computers operating Windows XP with SP3 or running Office 2003 products will continue to work after support ends. However, using unsupported software may increase the risk of viruses and other security threats.

    Users have the option to upgrade to a currently supported operating system or office productivity suite. The Microsoft “End of Support” pages for Windows XP and Office 2003 offer additional details.

    There are software vendors and service providers in the marketplace who offer assistance in migrating from Windows XP or Office 2003 to a currently supported operating system or office productivity suite. US-CERT does not endorse or support any particular product or vendor.

    Users who choose to continue using Windows XP after the end of support may mitigate some risks by using a web browser other than Internet Explorer. The Windows XP versions of some alternative browsers will continue to receive support temporarily. Users should consult the support pages of their chosen alternative browser for more details.

    References

    Revision History

    • March 10, 2014 - Initial Release
    • June 18, 2014 - A spelling correction was made.

    This product is provided subject to this Notification and this Privacy & Use policy.


  • TA14-017A: UDP-based Amplification Attacks
    Original release date: January 17, 2014 | Last revised: March 07, 2014

    Systems Affected

    Certain UDP protocols have been identified as potential attack vectors:

    • DNS
    • NTP
    • SNMPv2
    • NetBIOS
    • SSDP
    • CharGEN
    • QOTD
    • BitTorrent
    • Kad
    • Quake Network Protocol
    • Steam Protocol

    Overview

    A Distributed Reflective Denial of Service (DRDoS) attack is an emerging form of Distributed Denial of Service (DDoS) that relies on the use of publicly accessible UDP servers, as well as bandwidth amplification factors, to overwhelm a victim system with UDP traffic.

    Description

    UDP, by design, is a connection-less protocol that does not validate source IP addresses.  Unless the application-layer protocol uses countermeasures such as session initiation, it is very easy to forge the IP packet datagram to include an arbitrary source IP address [7].  When many UDP packets have their source IP address forged to a single address, the server responds to that victim, creating a reflected Denial of Service (DoS) Attack.

    Recently, certain UDP protocols have been found to have particular responses to certain commands that are much larger than the initial request.  Where before, attackers were limited linearly by the number of packets directly sent to the target to conduct a DoS attack, now a single packet can generate tens or hundreds of times the bandwidth in its response.  This is called an amplification attack, and when combined with a reflective DoS attack on a large scale it makes it relatively easy to conduct DDoS attacks.  

    To measure the potential effect of an amplification attack, we use a metric called the bandwidth amplification factor (BAF).  BAF can be calculated as the number of UDP payload bytes that an amplifier sends to answer a request, compared to the number of UDP payload bytes of the request [9] [10].

    The list of known protocols, and their associated bandwidth amplification factors, is listed below.  US-CERT would like to offer thanks to Christian Rossow for providing this information to us.  For more information on bandwith amplificatication factors, please see Christian's blog and associated research paper.

    ProtocolBandwidth Amplification FactorVulnerable Command
    DNS28 to 54see: TA13-088A [1]
    NTP556.9see: TA14-013A [2]
    SNMPv26.3GetBulk request
    NetBIOS3.8Name resolution
    SSDP30.8SEARCH request
    CharGEN358.8Character generation request
    QOTD140.3Quote request
    BitTorrent3.8File search
    Kad16.3Peer list exchange
    Quake Network Protocol63.9Server info exchange
    Steam Protocol5.5Server info exchange

     

    Impact

    Attackers can utilize the bandwidth and relative trust of large servers that provide the above UDP protocols to flood victims with unwanted traffic, a DDoS attack.

    Solution

    DETECTION

    Detection of DRDoS attacks is not easy, due to their use of large, trusted servers that provide UDP services.  As a victim, traditional DoS mitigation techniques may apply.

    As a network operator of one of these exploitable services, look for abnormally large responses to a particular IP address.  This may indicate that an attacker is using your service to conduct a DRDoS attack.

    MITIGATION

    Source IP Verification

    Because the UDP requests being sent by the attacker-controlled clients must have a source IP address spoofed to appear as the victim’s IP, the first step to reducing the effectiveness of UDP amplification is for Internet Service Providers to reject any UDP traffic with spoofed addresses. The Network Working Group of the Internet Engineering Task Force (IETF) released Best Current Practice 38 document in May 2000 and Best Current Practice 84 in March 2004 that describes how an Internet Service Provider can filter network traffic on their network to reject packets with source addresses not reachable via the actual packet’s path [3][4].  The changes recommended in these documents would cause a routing device to evaluate whether it is possible to reach the source IP address of the packet via the interface that transmitted the packet. If it is not possible, then the packet most likely has a spoofed source IP address. This configuration change would substantially reduce the potential for most popular types of DDoS attacks. As such, we highly recommend to all network operators to perform network ingress filtering if possible.  Note that it will not explicitly protect a UDP service provider from being exploited in a DRDoS (all network providers must use ingress filtering in order to completely eliminate the threat).

    To verify your network has implemented ingress filtering, download the open source tools from the Spoofer Project [5].

    Traffic Shaping

    Limiting responses to UDP requests is another potential mitigation to this issue.  This may require testing to discover the optimal limit that does not interfere with legitimate traffic.  The IETF released Request for Comment 2475 and Request for Comment 3260 that describes some methods to shape and control traffic [6] [8].  Most network devices today provide these functions in their software. 

    References

    Revision History

    • February 09, 2014 - Initial Release
    • March 07, 2014 - Updated page to include research links

    This product is provided subject to this Notification and this Privacy & Use policy.


  • TA14-013A: NTP Amplification Attacks Using CVE-2013-5211
    Original release date: January 13, 2014 | Last revised: February 05, 2014

    Systems Affected

    NTP servers

    Overview

    A Network Time Protocol (NTP) Amplification attack is an emerging form of Distributed Denial of Service (DDoS) that relies on the use of publically accessible NTP servers to overwhelm a victim system with UDP traffic.

    Description

    The NTP service supports a monitoring service that allows administrators to query the server for traffic counts of connected clients. This information is provided via the “monlist” command. The basic attack technique consists of an attacker sending a "get monlist" request to a vulnerable NTP server, with the source address spoofed to be the victim’s address.

    Impact

    The attack relies on the exploitation of the 'monlist' feature of NTP, as described in CVE-2013-5211, which is enabled by default on older NTP-capable devices. This command causes a list of the last 600 IP addresses which connected to the NTP server to be sent to the victim. Due to the spoofed source address, when the NTP server sends the response it is sent instead to the victim. Because the size of the response is typically considerably larger than the request, the attacker is able to amplify the volume of traffic directed at the victim. Additionally, because the responses are legitimate data coming from valid servers, it is especially difficult to block these types of attacks. The solution is to disable “monlist” within the NTP server or to upgrade to the latest version of NTP (4.2.7) which disables the “monlist” functionality.

    Solution

    Detection

    On a UNIX-platform, the command “ntpdc” will query existing NTP servers for monitoring data. If the system is vulnerable to exploitation, it will respond to the “monlist” command in interactive mode. By default, most modern UNIX and Linux distributions allow this command to be used from localhost, but not from a remote host. To test for monlist support, execute the following command at the command line:

    /usr/sbin/ntpdc <remote server>

    monlist

    Additionally, the “ntp-monlist” script is available for NMap, which will automatically display the results of the monlist command. If the system does not support the monitor query, and is therefore not vulnerable to this attack type, NMap will return an error type 4 (No Data Available) or no reply at all.

     

    Recommended Course of Action

    As all versions of ntpd prior to 4.2.7 are vulnerable by default, the simplest recommended course of action is to upgrade all versions of ntpd that are publically accessible to at least 4.2.7. However, in cases where it is not possible to upgrade the version of the service, it is possible to disable the monitor functionality in earlier versions of the software.

    To disable “monlist” functionality on a public-facing NTP server that cannot be updated to 4.2.7, add the “noquery” directive to the “restrict default” line in the system’s ntp.conf, as shown below:

    restrict default kod nomodify notrap nopeer noquery

    restrict -6 default kod nomodify notrap nopeer noquery

    References

    Revision History

    • January 13, 2014 - Initial Release

    This product is provided subject to this Notification and this Privacy & Use policy.


  • TA14-002A: Malware Targeting Point of Sale Systems
    Original release date: January 02, 2014 | Last revised: February 05, 2014

    Systems Affected

    Point of Sale Systems

    Overview

    Point of Sale Systems

    When consumers purchase goods or services from a retailer, the transaction is processed through what are commonly referred to as Point of Sale (POS) systems. POS systems consist of the hardware (e.g. the equipment used to swipe a credit or debit card and the computer or mobile device attached to it) as well as the software that tells the hardware what to do with the information it captures.

    When consumers use a credit or debit card at a POS system, the information stored on the magnetic stripe of the card is collected and processed by the attached computer or device. The data stored on the magnetic stripe is referred to as Track 1 and Track 2 data. Track 1 data is information associated with the actual account; it includes items such as the cardholder’s name as well as the account number. Track 2 data contains information such as the credit card number and expiration date.

    Description

    POS Targeting

    For quite some time, cyber criminals have been targeting consumer data entered in POS systems. In some circumstances, criminals attach a physical device to the POS system to collect card data, which is referred to as skimming. In other cases, cyber criminals deliver malware which acquires card data as it passes through a POS system, eventually exfiltrating the desired data back to the criminal. Once the cybercriminal receives the data, it is often trafficked to other suspects who use the data to create fraudulent credit and debit cards.

    As POS systems are connected to computers or devices, they are also often enabled to access the internet and email services. Therefore malicious links or attachments in emails as well as malicious websites can be accessed and malware may subsequently be downloaded by an end user of a POS system. The return on investment is much higher for a criminal to infect one POS system that will yield card data from multiple consumers.

    Impact

    There are several types of POS malware in use, many of which use a memory scraping technique to locate specific card data. Dexter, for example, parses memory dumps of specific POS software related processes looking for Track 1 and Track 2 data. Stardust, a variant of Dexter not only extracts the same track data from system memory, it also extracts the same type of information from internal network traffic. Researchers surmise that Dexter and some of its variants could be delivered to the POS systems via phishing emails or the malicious actors could be taking advantage of default credentials to access the systems remotely, both of which are common infection vectors. Network and host based vulnerabilities, such as weak credentials accessible over Remote Desktop, open wireless networks that include a POS machine and physical access (unauthorized or misuse) are all also candidates for infection.

    Solution

    POS System Owner Best Practices

    Owners and operators of POS systems should follow best practices to increase the security of POS systems and prevent unauthorized access.

    • Use Strong Passwords: During the installation of POS systems, installers often use the default passwords for simplicity on initial setup. Unfortunately, the default passwords can be easily obtained online by cybercriminals. It is highly recommended that business owners change passwords to their POS systems on a regular basis, using unique account names and complex passwords.
    • Update POS Software Applications: Ensure that POS software applications are using the latest updated software applications and software application patches. POS systems, in the same way as computers, are vulnerable to malware attacks when required updates are not downloaded and installed on a timely basis.
    • Install a Firewall: Firewalls should be utilized to protect POS systems from outside attacks. A firewall can prevent unauthorized access to, or from, a private network by screening out traffic from hackers, viruses, worms, or other types of malware specifically designed to compromise a POS system.
    • Use Antivirus: Antivirus programs work to recognize software that fits its current definition of being malicious and attempts to restrict that malware’s access to the systems. It is important to continually update the antivirus programs for them to be effective on a POS network.
    • Restrict Access to Internet: Restrict access to POS system computers or terminals to prevent users from accidentally exposing the POS system to security threats existing on the internet. POS systems should only be utilized online to conduct POS related activities and not for general internet use.
    • Disallow Remote Access: Remote access allows a user to log into a system as an authorized user without being physically present. Cyber Criminals can exploit remote access configurations on POS systems to gain access to these networks. To prevent unauthorized access, it is important to disallow remote access to the POS network at all times.

    Consumer Remediation

    Fraudulent charges to a credit card can often be remediated quickly by the issuing financial institution with little to no impact on the consumer. However, unauthorized withdrawals from a debit card (which is tied to a checking account) could have a cascading impact to include bounced checks and late-payment fees.

    Consumers should routinely change debit card PINs. Contact or visit your financial institutions website to learn more about available fraud liability protection programs for your debit and credit card accounts. Some institutions offer debit card protections similar to or the same as credit card protections.

    If consumers have a reason to believe their credit or debit card information has been compromised, several cautionary steps to protect funds and prevent identity theft include changing online passwords and PINs used at ATMs and POS systems; requesting a replacement card; monitoring account activity closely; and placing a security freeze on all three national credit reports (Equifax, Experian and TransUnion). A freeze will block access to your credit file by lenders you do not already do business with. Under federal law, consumers are also entitled to one free copy of their credit report every twelve months through AnnualCreditReport.com.

    Consumers may also contact the Federal Trade Commission (FTC) at (877) 438-4338 or via their website at www.consumer.gov/idtheft or law enforcement to report incidents of identity theft.

    References

    Revision History

    • January 2, 2014 - Initial Release

    This product is provided subject to this Notification and this Privacy & Use policy.


  • TA13-317A: Microsoft Updates for Multiple Vulnerabilities
    Original release date: November 13, 2013 | Last revised: November 16, 2013

    Systems Affected

    • Windows Operating System and Components
    • Microsoft Office
    • Internet Explorer

    Overview

    Select Microsoft software products contain multiple vulnerabilities. Microsoft has released updates to address these vulnerabilities.

    Description

    The Microsoft Security Bulletin Summary for November 2013 describes multiple vulnerabilities in Microsoft software. Microsoft has released updates to address these vulnerabilities. The November Security Bulletin includes a patch for the new “watering hole” campaign which utilizes a US-based website that specializes in domestic and international security policy.

    Impact

    These vulnerabilities could allow remote code execution, elevation of privilege, information disclosure or denial of service.

    Solution

    Apply Updates

    Microsoft has provided updates for these vulnerabilities in the Microsoft Security Bulletin Summary for November 2013, which describes any known issues related to the updates. Administrators are encouraged to note these issues and test for any potentially adverse effects. In addition, administrators should consider using an automated update distribution system such as Windows Server Update Services (WSUS). Home users are encouraged to enable automatic updates.

    References

    Revision History

    • November 13, 2013: Initial Release

    This product is provided subject to this Notification and this Privacy & Use policy.