For Home

Virus Profile: W32/Autorun.worm.aadc

Threat Search
Print
   
Virus Profile information details
Risk Assessment: Home Low | Corporate Low
Date Discovered: 7/4/2012
Date Added: 7/4/2012
Origin: N/A
Length: VARIES
Type: Trojan
Subtype: Win32
DAT Required: 6762
Removal Instructions
   
 
 
   

Description

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 -

  • Ikarus      - Worm.Win32.Rombrast
  • Microsoft - Worm:Win32/Rombrast.gen!A
  • Symantec - W32.SillyFDC
  • Nod32     - a variant of Win32/AutoRun.Agent.AGC

Indication of Infection

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

Methods 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, email spam, etc.
   

Virus Characteristics

------------------Updated on 8 August 2012-----------------------------

Aliases

Kaspersky - Trojan-Ransom.Win32.Gimemo.wap
Symantec - W32.SillyFDC
NOD32 - a variant of Win32/Injector.TGD
Microsoft - PWS:Win32/Zbot.AFS

“W32/Autorun.worm.aadc” is a worm detection written in AutoIT script and it’s a network-aware worm that attempts to replicate across the existing network

Upon execution the worm inject into the system process “Explorer.exe” and connects to the below IP Addresses 193.107.[Removed].253 ,193.107.[Removed].249 in order to make a network connection to the following URL through the remote port 80.

  • LrS[Removed]ger.ru
  • Zvh[Removed]ion.ru

And creates the Following files to the below location

  • %Temp%\~DF424.tmp
  • %Appdata%\Microsoft\b17ef6c.exe
  •  : [RemovableDrive]\ b17ef6c.exe

And drops an autorun.inf file into the root of all removable drives and mapped drives in an attempt to autorun an executable when the drive is accessed.

Also it creates the shortcut files (.lnk) for each and every directories available in the removable drive.

The Autorun.inf file will look like this

[autorun]
open= b17ef6c.exe

The following registry keys has been added

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\{36FC9E60-C465-11CF-8056-444553540000}\0006
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\{4D36E967-E325-11CE-BFC1-08002BE10318}\0003
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\{71A27CDD-812A-11D0-BEC7-08002BE2092F}\0003

And the below registry values has been added to the system

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\{36FC9E60-C465-11CF-8056-444553540000}\0006\

  • DriverFlags = 0x00000001
  • InfPath = "usbstor.inf"
  • InfSection = "USBSTOR_BULK"
  • InfSectionExt = ".NT"
  • ProviderName = "Microsoft"
  • DriverDateData =  00 80 62 C5 C0 01 C1 01
  • DriverDate = "7-1-2001"
  • DriverVersion = "5.1.2600.0"

The below mentioned registry key confirms that the worm executes every time when windows starts.

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\
b17ef6c.exe = %AppData%\Microsoft\b17ef6c.exe

Also the Trojan collects the system information from the compromised system using the below commands

  • GetNativeSystemInfo

The following APIs used to hide the malware files in the removable drive:

  • FindFirstFileW
  • FindNextFileW
  • FindFirstFileExW
  • NtQueryDirectoryFile

--------------------------------------------------------------------------

"W32/Autorun.worm.aadc" is worm that may propagate via removable drives or network shares. Also, it is designed to download other malicious files from websites.

Upon execution the worm inject into the windows explorer (Explorer.exe) and connects to the below IP Address

  • 193.107. [Removed].254
  • 193.107. [Removed].249

In order to make a connection to the following URL through the remote port 80.

  • RbjO5[Removed]et.ru
  • JXxhN[Removed]et.ru
  • rFn7B[Removed]ads.ru 

And copies of itself in to the below location

  • %AppData%\ Microsoft\b17ef6c.exe
  • : [RemovableDrive]\ b17ef6c_a.exe

Above mentioned file is hidden using rootkit mechanism and drops an autorun.inf file into the root of all removable drives and mapped drives in an attempt to autorun an executable when the drive is accessed.

The file "AutoRun.inf" is pointing to the malware binary executable, when the removable or networked drive is accessed from a machine supporting the Autorun feature, the malware is launched automatically.

The Autorun.inf file will look like this

  • [Autorun]
  • open=b17ef6c_a.exe

The following registry value has been added to the system.

  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\SuperHidden = 1
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Hidden = 1
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\HideFileExt =0
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\ShowInfoTip = 1
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\HideIcons = 0
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\SeparateProcess =0

The below mentioned registry values ensures that the worm gets executed whenever the System starts.

  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\
    "b17ef6c" = "%AppData%\Microsoft\b17ef6c.exe"
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\
    "b17ef6c" = "%AppData%\Microsoft\b17ef6c.exe"

The following APIs used to hide the malware files in the removable drive:

  • FindFirstFileW
  • FindNextFileW
  • FindFirstFileExW
  • NtQueryDirectoryFile

Also getting the current System information from the compromised system using the below commands

  • GetNativeSystemInfo
  • Get Hostname

   

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.