Analysis by: Karl Dominguez
 PLATFORM:

Windows 2000, XP, 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 may be downloaded by other malware/grayware from remote sites. It may be unknowingly downloaded by a user while visiting malicious websites. It may be downloaded from remote sites by other malware. However, as of this writing, the said sites are inaccessible.

It connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size: 16,384 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 24 Jul 2010

Arrival Details

This Trojan may be downloaded by the following malware/grayware from remote sites:

  • http://{BLOCKED}myhouse.us/from/wincrng.exe

It may be unknowingly downloaded by a user while visiting malicious websites.

It may be downloaded from remote site(s) by the following malware:

  • TROJ_DLOADR.WM

However, as of this writing, the said sites are inaccessible.

Installation

This Trojan adds the following mutexes to ensure that only one of its copies runs at any one time:

  • {current date} - with the format of [year][month][day]

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\Run
{malware file name} = {malware path and file name}

Backdoor Routine

This Trojan connects to the following websites to send and receive information:

  • http://{BLOCKED}myhouse.us/test/chkver.php - connects to this URL to check for a newer version of itself
  • http://{BLOCKED}myhouse.us/test/chkpage.php - connects to this URL to download an updated copy of itself or another malware

Download Routine

This Trojan saves the files it downloads using the following names:

  • %Current%\ctfmon.exe

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI PATTERN File: 7.446.02
VSAPI PATTERN Date: 08 Sep 2010
VSAPI PATTERN Date: 9/8/2010 12:00:00 AM
FIRST VSAPI PATTERN FILE: 7.336.02
FIRST VSAPI PATTERN DATE: 24 Jul 2010

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_CHIFRAX.BU

    TROJ_DLOADR.WM

Step 3

Identify and terminate files detected as TROJ_CHIFRAX.BU

[ 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 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\CurrentVersion\Run
    • {malware file name} = {malware path and file name}

Step 5

Search and delete these files

[ 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. %Current%\ctfmon.exe

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_CHIFRAX.BU. 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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