Analysis by: Michael Cabel
ALIASES:

Microsoft: TrojanDownloader:Win32/Renos.LX; Mcafee: Downloader-CEW.ai

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

It modifies the Internet Explorer Zone Settings.

  TECHNICAL DETAILS

File Size: 122,368 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 21 Apr 2011

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.

Installation

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

  • %Windows%\Cgowua.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

Other System Modifications

This Trojan adds the following registry keys as part of its installation routine:

HKEY_CURRENT_USER\Software\K8CE6CA1JO

Web Browser Home Page and Search Page Modification

This Trojan modifies the Internet Explorer Zone Settings.

  SOLUTION

Minimum Scan Engine: 8.900

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 process file/s detected as TROJ_KRYPTIK.CJD

[ Learn More ]

*Note: If the detected file/s is/are not displayed in theWindows Task Manager, 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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_CURRENT_USER\Software
    • K8CE6CA1JO

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_KRYPTIK.CJD. 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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