WORM_CRIDEX.BC

April 24, 2014
 ALIASES:

Worm:Win32/Cridex.E (Microsoft); PWS-Zbot.gen.ad (McAfee); W32.Cridex (Symantec); Trojan-Spy.Win32.Zbot.qsyb (Kaspersky); Troj/Agent-AEXT (Sophos); Trojan.Win32.Cridex.tau (v) (Sunbelt); Trojan horse PSW.Generic12.NWQ (AVG)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

81,920 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

14 Apr 2014

Arrival Details

This worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This worm drops the following copies of itself into the affected system:

  • %User Profile%\Application Data\KB00892240.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It creates the following folders:

  • %User Profile%\Application Data\46484211

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
KB00892240.exe = "%User Profile%\Application Data\KB00892240.exe "

Other System Modifications

This worm adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\S46484211

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CF048F32E

Other Details

This worm connects to the following possibly malicious URL:

  • http://updatecheck.{BLOCKED}o.ua/Qyu6/+3u8PCAAAA/ujsXhDAAAA

It deletes itself after execution.

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry key

[ 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 NT
    • S46484211
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT
    • CF048F32E

Step 4

Delete this registry 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
    • KB00892240.exe = "%User Profile%\Application Data\KB00892240.exe "

Step 5

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\46484211

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_CRIDEX.BC. 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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