Analysis by: jasperm


Windows 2000, XP, Server 2003


  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes


This Trojan executes commands from a remote malicious user, effectively compromising the affected system.


Ports: Random TCP ports
File Size: Varies
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 29 Apr 2010
Payload: Connects to websites to send and receive information


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

  • %System%\{random file name}.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 Trojan registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

Services\{service name}
ImagePath = %System%\{malware file name}.EXE

Services\{service name}
Start = 2

Backdoor Routine

This Trojan executes the following commands from a remote malicious user:

  • Downloads and executes files from certain websites
  • Starts and stops certain IIS services

Other Details

This Trojan does the following:

  • Connects to any of the following URLs via random TCP ports to send and receive information:
    • http://xhsb.{BLOCKED}
    • http://wanmei8013.{BLOCKED}
    • http://avzhan1.{BLOCKED}
    • {BLOCKED}
  • Sends data that contains the following information:
    • Computer Name
    • Locale Info
    • OS Version
    • Product Name
    • CPU Speed
    • Memory Size
  • Manifests similar behavior and characteristics as the following malware:


Minimum Scan Engine: 8.900
VSAPI PATTERN File: 7.137.80
VSAPI PATTERN Date: 29 Apr 2010
VSAPI PATTERN Date: 4/29/2010 12:00:00 AM

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

Identify and terminate files detected as MAL_SCAR-1

[ Learn More ]
  1. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  2. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • {service name}

Step 4

Scan your computer with your Trend Micro product to delete files detected as MAL_SCAR-1. 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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