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Virus:W32/Sality.AA

First posted on 10 June 2009.
Source: SecurityHome

Aliases :

Virus:W32/Sality.AA is also known as Virus:Win32/Sality.AM (Microsoft), W32.Sality.AE (Symantec).

Explanation :

A program that secretly and maliciously integrates itself into program or data files. It spreads by integrating itself into more files each time the host program is run.

Additional DetailsVirus:W32/Sality.AA is an appending file infector virus that uses an entry point obscuring technique to hide its presence on the system.

The virus attempts to terminate running antivirus programs. It can also download and install additional malware on the system.

Installation

The following file may be dropped on the system:


• [System]drivers[random].sys
The file is detected as Virus.Win32.Sality.ab.

It will copy itself to removal drives and shared folders as one of the following :


• [randomname].exe
• [randomname].pif
• [randomname].cmd
An autorun.inf file will be created on the drive so that the malware will be executed when it is connected to a computer.

It also modifies %windir%SYSTEM.INI by adding the following section :


• [MCIDRV_VER]
DEVICE=[random alphanumeric string]

Infection

Once on the system, the virus searches the hard disk (starting with C:) and infects any files with the following extensions:


• .exe
• .scr
It also infects files with .EXE extensions that are referenced as data in the following registry keys:


• [HKCUSoftwareMicrosoftWindowsCurrentVersion
un]
• [HLKMSoftwareMicrosoftWindowsCurrentVersion
un]
The virus appends itself by creating a new 73728 bytes sized section named "[random characters]data". The section contains Sality.AA's obfuscated code.

Entry Point Obscuration

On infection, the first 327 bytes from the file's entry point are overwritten with deobfuscation code. If the user executes the infected file, Sality.AA restores the original entry point code and launches the program in order to mask its presence.

Registry

When run, Sality.AA creates a mutex to ensure only one instance is running. It then modifies a large range of registry entries. The virus attempts to disable processes and services containing strings related to major antivirus software.

Network Connection

The malware connects to the following website to verify an Internet connection :


• http://www.microsoft.com
The malware may connect to the following sites to download and execute additional malware :


• http://kukutrustnet777.info/[...].gif
• http://kukutrustnet888.info/[...].gif
• http://kukutrustnet987.info/[...].gif
• http://www.musikrajt.sk/[...].gif
• http://macedonia.my1.ru/[...].gif
• http://jrsx.jre.net.cn/[...].gif
• http://www.musikrajt.wz.cz/[...].gif
• http://www.solidarnosc.org.pl/lublin/[...].gif
• http://gotcha.goldeye.info/[...].gif
Downloaded files are encrypted. They are unencrypted by the malware to the %temp% folder and executed.

The following URLs may possibly be used to get further instructions:


• http://89.119.67.154/[...]/
• http://klkjwre77638dfqwieuoi888.[...]/
• http://kukutrustnet777888.[...]/

Last update 10 June 2009

 

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