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TROJ_CRYPTIC.BWH

October 08, 2012
 Analysis by: Sabrina Lei Sioting
 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 deletes itself after execution.

  TECHNICAL DETAILS

File Size:

320,000 bytes

File Type:

PE

Memory Resident:

No

Initial Samples Received Date:

15 Mar 2011

Installation

This Trojan drops the following files:

  • %System Root%\Documents and Settings%\All Users\Application Data\iChGbNa24901\iChGbNa24901.exe - detected as TROJ_FAKEAV.SMIE

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It creates the following folders:

  • %System Root%\Documents and Settings%\All Users\Application Data\iChGbNa24901
  • %System Root%\Documents and Settings%\All Users\Application Data\iChGbNa24901\iChGbNa24901

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
iChGbNa24901 = "%System Root%\Documents and Settings%\All Users\Application Data\iChGbNa24901\iChGbNa24901.exe"

Other Details

This Trojan deletes itself after execution.

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

7.902.03

FIRST VSAPI PATTERN DATE:

15 Mar 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

Remove malware files dropped/downloaded by TROJ_CRYPTIC.BWH

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
    • iChGbNa24901 = "%System Root%\Documents and Settings%\All Users\Application Data\iChGbNa24901\iChGbNa24901.exe"

Step 4

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.
  • %System Root%\Documents and Settings%\All Users\Application Data\iChGbNa24901

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_CRYPTIC.BWH. 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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