INFO SEC_ AAEH Systems Affected

TA15-098A: AAEH

04/09/2015 12:00 AM EDT

Original release date: April 09, 2015

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

AAEH is a family of polymorphic downloaders created with the primary purpose of downloading other malware, including password stealers, rootkits, fake antivirus, and ransomware.

The United States Department of Homeland Security (DHS), in collaboration with Europol, the Federal Bureau of Investigation (FBI) and the Department of Justice (DOJ), released this Technical Alert to provide further information about the AAEH botnet, along with prevention and mitigation recommendations.

Description

AAEH is often propagated across networks, removable drives (USB/CD/DVD), and through ZIP and RAR archive files. Also known as VObfus, VBObfus, Beebone or Changeup, the polymorphic malware has the ability to change its form with every infection. AAEH is a polymorphic downloader with more than 2 million unique samples. Once installed, it morphs every few hours and rapidly spreads across the network.  AAEH has been used to download other malware families, such as Zeus, Cryptolocker, ZeroAccess, and Cutwail.

Impact

A system infected with AAEH may be employed to distribute malicious software, harvest users' credentials for online services, including banking services, and extort money from users by encrypting key files and then demanding payment in order to return the files to a readable state. AAEH is capable of defeating anti-virus products by blocking connections to IP addresses associated with Internet security companies and by preventing anti-virus tools from running on infected machines.  

Solution

Users are recommended to take the following actions to remediate AAEH 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 AAEH from your system.

Note: AAEH blocks AV domain names thereby preventing infected users from being able to download remediation tools directly from an AV company. The links below will take you to the tools at the respective AV sites. In the event that the tools cannot be accessed or downloaded from the vendor site, the tools are accessible from Shadowserver (http://aaeh.shadowserver.org).

The below 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

• F-Secure Online Scanner for Windows Vista, 7 and 8
• F-Secure Removal Tools for Windows XP
• McAfee Stinger for Windows XP SP2, 2003 SP2, Vista SP1, 2008, 7 and 8
• Microsoft Safety Scanner for Windows 8.1, Windows 8, Windows 7, Windows Vista, and Windows XP
• Sophos Virus Removal for Windows XP SP2 and above
• Trend Micro Threat Detector for Windows XP, Windows Vista, Windows 7, Windows 8/8.1, Windows Server 2003/2008, and 2008 R2

Revision History

• April 9, 2015: Initial Release