WORM_FAKER.B

November 01, 2012
 Analysis by: Mark Joseph Manahan
 ALIASES:

Worm:Win32/Fakerecy.A (Microsoft), Win32/VB.AQT trojan (Eset), Worm:Win32/Fakerecy.A (Symantec), FakeRecycled (McAfee)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Via physical/removable drives, Downloaded from the Internet, Dropped by other malware

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

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

  TECHNICAL DETAILS

File Size:

20,480 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

28 Sep 2012

Arrival Details

This worm arrives via removable drives.

It 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 adds the following possibly malicious files or file components:

  • {drive letter}:\Recycled\INFO2
  • {drive letter}:\Recycled\desktop.ini

It creates the following folders:

  • {drive letter}:\Recycled
  • {drive letter}:\Recycled\Recycled

Autostart Technique

This worm drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

  • %User Startup%\ctfmon.exe

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

Propagation

This worm drops the following copies of itself in all physical and removable drives:

  • {drive letter}:\Recycled\Recycled\ctfmon.exe

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

[autorun]
shellexecute=Recycled\ctfmon.exe
shell\Open(&0)\command=Recycled\ctfmon.exe
shell=Open(&0)

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

9.428.01

FIRST VSAPI PATTERN DATE:

28 Sep 2012

VSAPI OPR PATTERN File:

9.429.00

VSAPI OPR PATTERN Date:

29 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

Search and delete AUTORUN.INF files created by WORM_FAKER.B that contain these strings

[ Learn More ]
 
  • [autorun]
  • shellexecute=Recycled\ctfmon.exe
  • shell\Open(&0)\command=Recycled\ctfmon.exe
  • shell=Open(&0)

Step 3

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.
  • {drive letter}:\Recycled

Step 4

Scan your computer with your Trend Micro product to delete files detected as WORM_FAKER.B. 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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