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BKDR_QAKBOT.EX

October 09, 2012
 Analysis by: Mark Joseph Manahan
 ALIASES:

Win32/Qbot.BB trojan (Eset), Backdoor:Win32/Qakbot (Microsoft), W32/Pinkslipbot.gen.bf (McAfee), W32.Qakbot (Symantec)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This backdoor deletes itself after execution.

  TECHNICAL DETAILS

File Size:

187,392 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

17 Sep 2012

Installation

This backdoor adds the following folders:

  • %User Profile%\Application Data\Microsoft\{Random}

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

It drops the following copies of itself into the affected system:

  • %User Profile%\Application Data\Microsoft\{Random}\{Random}.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

It adds the following possibly malicious files or file components:

  • %User Profile%\APPLICATION DATA\MICROSOFT\{Random}\{Random}.dll

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{Random} = "%User Profile%\Application Data\Microsoft\{Random}\{Random}.exe"

It modifies the following registry entry(ies) to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
ctfmon.exe = "%User Profile%\Application Data\Microsoft\{Random}\{Random}.exe" /c %System%\ctfmon.exe"

(Note: The default value data of the said registry entry is "%System%\ctfmon.exe".)

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}istr.in
  • {BLOCKED}vtkn.{BLOCKED}n.ua
  • {BLOCKED}uytdk.info
  • {BLOCKED}asudskfoe.org
  • {BLOCKED}iakfuuasd.net
  • {BLOCKED}s.{BLOCKED}v.ua
  • {BLOCKED}m.{BLOCKED}v.ua
  • {BLOCKED}n.org
  • {BLOCKED}nz.net
  • {BLOCKED}mausj.org

It deletes itself after execution.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

9.402.03

FIRST VSAPI PATTERN DATE:

18 Sep 2012

VSAPI OPR PATTERN File:

9.403.00

VSAPI OPR PATTERN Date:

18 Sep 2012

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Scan your computer with your Trend Micro product and note files detected as BKDR_QAKBOT.EX

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Delete the registry entry with an unknown data value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {Random} = "%User Profile%\Application Data\Microsoft\{Random}\{Random}.exe"

Step 5

Restore this modified registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator’s help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • From: ctfmon.exe = "%User Profile%\Application Data\Microsoft\{Random}\{Random}.exe" /c %System%\ctfmon.exe"
      To: ctfmon.exe = "%System%\ctfmon.exe"

Step 6

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.  
  • %User Profile%\Application Data\Microsoft\{random}

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_QAKBOT.EX. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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