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TROJ_AGENT.AFJ

June 10, 2013
 Analysis by: Nikko Tamana
 ALIASES:

W32/Yakes.CRJS!tr (Fortinet), Trojan.Win32.Agent (Ikarus), Trojan.Win32.Yakes.crjs (Kaspersky), Trojan:Win32/Stoberox.B (Microsoft)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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.

  TECHNICAL DETAILS

File Size:

110,592 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

06 Jun 2013

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
Run = "{Malware Path and File Name}.{Extension}"

NOTES:

This malware creates folders in random directories with different folder names. It then drops a copy in the created folder with the same name as the folder name with the varying file extension.

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

9.964.03

FIRST VSAPI PATTERN DATE:

06 Jun 2013

VSAPI OPR PATTERN File:

9.965.00

VSAPI OPR PATTERN Date:

07 Jun 2013

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

Scan your computer with your Trend Micro product and note files detected as TROJ_AGENT.AFJ

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 NT\CurrentVersion\Windows
    • Run = "{Malware Path and File Name}.{Extension}"

Step 5

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.
  • {Malware Path}

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_AGENT.AFJ. 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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