Analysis by: Michael Cabel
 PLATFORM:

Windows 2000, Window XP, Window 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 executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size: Varies
Memory Resident: Yes
Initial Samples Received Date: 20 May 2011

Arrival Details

This Trojan may be downloaded from the following remote sites:

  • http://{BLOCKED}ch.com/apps/vpn-client/setup.exe
  • http://{BLOCKED}ch.com/apps/vpn-client/setup.exe

Installation

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

  • %Application Data%\Microsoft\svcrshost.exe

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

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Svcrshost Service = "%Application Data%\Microsoft\svcrshost.exe"

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\hol.txt
  • %User Temp%\so.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 8.166.14
FIRST VSAPI PATTERN DATE: 20 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

Terminate a malware/grayware process

[ Learn More ]

*Note: If the detected process is not displayed in theWindows Task Manager, continue doing the next steps.

    %Application Data%\Microsoft\svcrshost.exe

Step 3

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Svcrshost Service = "%Application Data%\Microsoft\svcrshost.exe"

Step 4

Search and delete this file

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files and folders in the search result.
%User Temp%\hol.txt
%User Temp%\so.exe

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPPR.CQ. 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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