W32/Sirefef.f

This page shows details and results of our analysis on the malware W32/Sirefef.f

Overview

This is a Trojan detection. Unlike viruses, Trojans do not self-replicate. They are spread manually, often under the premise that they are beneficial or wanted. The most common installation methods involve system or security exploitation, and unsuspecting users manually executing unknown programs. Distribution channels include e-mail, malicious or hacked Web pages, Internet Relay Chat (IRC), peer-to-peer networks, etc.

Aliases : - 

    • F-Secure - Trojan.Sirefef.AN
    • Kaspersky - Backdoor.Win32.ZAccess.aqo
    • Microsoft - Trojan:Win32/Sirefef.P
    • NOD32 - a variant of Win32/Sirefef.CR


Minimum DAT

6526 (2011-11-10)

Updated DAT

6531 (2011-11-15)

Minimum Engine

5400.1158

File Length

varies

Description Added

2011-11-10

Description Modified

2012-03-21

Malware Proliferation

Characteristics

----- Updated on 30-Jan-2012 ------------

Aliases : -

    • AVG - Dropper.Agent.ARQJ
    • Ikarus - Backdoor.Win32.Smadow
    • Kaspersky - Backdoor.Win32.ZAccess.aqo
    • Microsoft - Trojan:Win32/Sirefef.P

Upon execution the Trojan connects to the following site s[removed].histats.com through the remote port 53 to download other malicious files.

The following file has been added to the system.

    • %Windir%\[random name]

The following registry keys have been added to the system.

    • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\[random name]

The following registry Values have been added to the system.

    • [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\[random name]]
      Type = 0x00000001
      Start = 0x00000003
      ImagePath = "\systemroot\[random name]: [random name].exe"

[Note C:\WINDOWS is %Windir%]

--------

Upon execution, the Trojan drops a file into the below mentioned location

    • %WinDir%\[Random Number] [Detected as ZeroAccess.a]

Also the Trojan has communication with the below mentioned site:

    • [removed]1.histats.com

The following registry key has been added

    • HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\[Random Name]
    • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\[Random Name]

The following registry values have been added

    • HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\[Random Name]
      Type = 0x00000001
      Start = 0x00000003
      ImagePath = "%WinDir%\[Random Number].exe"
    • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\[Random Name]
      Type = 0x00000001
      Start = 0x00000003
      ImagePath = "%WinDir%\[Random Number].exe"

The above registry entry confirms that, the Trojan creates a service with the random name and executes itself whenever windows starts.

Note [%WinDir% - C:\WINDOWS]

 

Symptoms

These symptoms of this detection are the files, registry, and network communication referenced in the characteristics section.

Method of Infection

Trojans do not self-replicate. They are spread manually, often under the premise that the executable is something beneficial. Distribution channels include IRC, peer-to-peer networks, newsgroup postings, e-mail, etc.

Removal

All Users:

Please use the following instructions for all supported versions of Windows to remove threats and other potential risks:

1.Disable System Restore .

2.Update to current engine and DAT files for detection and removal.

3.Run a complete system scan.

Modifications made to the system Registry and/or INI files for the purposes of hooking system startup, will be successfully removed if cleaning with the recommended engine and DAT combination (or higher).

1. Please go to the Microsoft Recovery Console and restore a clean MBR.

On windows XP:

Insert the Windows XP CD into the CD-ROM drive and restart the computer.
When the "Welcome to Setup" screen appears, press R to start the Recovery Console.
Select the Windows installation that is compromised and provide the administrator password
Issue 'fixmbr' command to restore the Master Boot Record
Follow onscreen instructions
Reset and remove the CD from CD-ROM drive.


On Windows Vista and 7:

Insert the Windows CD into the CD-ROM drive and restart the computer.
Click on "Repair Your Computer"
When the System Recovery Options dialog comes up, choose the Command Prompt.
Issue 'bootrec /fixmbr' command to restore the Master Boot Record
Follow onscreen instructions
Reset and remove the CD from CD-ROM drive.

Variants