Analysis by: kathleenno
ALIASES:

W32.SillyFDC (Symantec); Worm:Win32/Wergimog.A (Microsoft); Trojan.Win32.Pincav.arsf (Kaspersky); Generic.dx!wvw (Mcafee); Mal/Pincav-E (Sophos)

 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: Propagates via removable drives

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 drops copies of itself in all removable drives. 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: 107,601 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 06 May 2011
Payload: Drops files

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:

  • %System%\service{random numbers}.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

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
Adobe Reader Speed Launcher = %System%\service{random numbers}.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Adobe Reader Speed Launcher = %System%\service{random numbers}.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Adobe Reader Speed Launcher = %System%\service{random numbers}.exe

Propagation

This worm drops copies of itself in all removable drives.

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:

;{garbage characters}
[autorun]
;{garbage characters}
action=Open folder to view files
;{garbage characters}
icon=shell32.dll,4
;{garbage characters}
open=RECYCLER\autorun.exe
;{garbage characters}
shell\Explore=Explore
;{garbage characters}
shell\Explore\command=RECYCLER\autorun.exe
;{garbage characters}
shell=Explore
;{garbage characters}
UseAutoPlay=1
;{garbage characters}

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 8.140.10
FIRST VSAPI PATTERN DATE: 06 May 2011

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 WORM_PINCAV.FV

Step 3

Restart in Safe Mode

[ Learn More ]

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
    • Adobe Reader Speed Launcher = %System%\service{random numbers}.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Adobe Reader Speed Launcher = %System%\service{random numbers}.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • Adobe Reader Speed Launcher = %System%\service{random numbers}.exe

Step 5

Search and delete AUTORUN.INF files created by WORM_PINCAV.FV that contain these strings

[ Learn More ]
;{garbage characters}
[autorun]
;{garbage characters}
action=Open folder to view files
;{garbage characters}
icon=shell32.dll,4
;{garbage characters}
open=RECYCLER\autorun.exe
;{garbage characters}
shell\Explore=Explore
;{garbage characters}
shell\Explore\command=RECYCLER\autorun.exe
;{garbage characters}
shell=Explore
;{garbage characters}
UseAutoPlay=1
;{garbage characters}

Step 6

Scan your computer with your Trend Micro product to delete files detected as WORM_PINCAV.FV. 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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