TROJ_RANSOM.WI

March 31, 2011
 Analysis by: kathleenno
 ALIASES:

W32/Pinkslipbot.gen.aj (McAfee)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This Trojan ransomware possesses increased potential for damage, propagation, or both. Specifically, it locks the affected machine by suspending all running threads found in EXPLORER.EXE. It then displays a message written in German in an attempt to extort money from the affected users.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

It connects to a legitimate site to determine the system's network information.

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

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size:

93,696 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

30 Mar 2011

Payload:

Connects to URLs/IPs, Terminates processes, Compromises system security, Renders the system unresponsive, Retrieves network information

Arrival Details

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

Autostart Technique

This Trojan modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "{malware path and file name}"

(Note: The default value data of the said registry entry is Explorer.exe.)

Process Termination

This Trojan terminates the following processes if found running in the affected system's memory:

  • taskmgr.exe

Other Details

This Trojan connects to the following website to send and receive information:

  • http://{BLOCKED}.{BLOCKED}.187.232/s.php?a=2

NOTES:

This ransomware Trojan locks the affected machine by suspending all running threads found in EXPLORER.EXE. It then displays the following message written in German in an attempt to extort money from the affected users:

It also connects to the following legitimate site to determine the system's network information:

  • http://tools.ip2location.com/ib2/

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

7.940.16

FIRST VSAPI PATTERN DATE:

30 Mar 2011

VSAPI OPR PATTERN File:

7.941.00

VSAPI OPR PATTERN Date:

31 Mar 2011

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

Identify and delete files detected as TROJ_RANSOM.WI using either the Startup Disk or Recovery Console

[ Learn More ]

Step 3

Restore this modified 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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Shell = "{malware path and file name}"
      To: Shell = "Explorer.exe"

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_RANSOM.WI. 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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