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TROJ_RIMECUD.DL

October 08, 2012
 Analysis by: Christopher Daniel So
 ALIASES:

Trojan:Win32/Ircbrute (Microsoft); Net-Worm.Win32.Kolab.usv (Kaspersky); Trojan.Win32.Ircbrute (GFI-Sunbelt); W32/Kolab.XUDV!tr.dldr (Fortinet)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW


The downloaded file is detected as WORM_RIMECUD.ZB.

This Trojan may be downloaded from remote sites by other malware.

It connects to certain URLs. It may do this to remotely inform a malicious user of its installation. It may also do this to download possibly malicious files onto the computer, which puts the computer at a greater risk of infection by other threats. It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size:

66,045 bytes

File Type:

PE

Memory Resident:

Yes

Initial Samples Received Date:

25 Feb 2011

Payload:

Downloads files

Arrival Details

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

  • WORM_RIMECUD.ZB

It may be downloaded from the following remote sites:

  • http://b.{BLOCKED}pgirl.com/myms.exe

Installation

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

  • %Windows%\wjdrive32.exe

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

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Microsoft Driver Setup = "%Windows%\wjdrive32.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
Microsoft Driver Setup = "%Windows%\wjdrive32.exe"

Other System Modifications

This Trojan creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
{malware path and file name} = "{malware path and file name}:*:%Windows%\wjdrive32.exe"

Download Routine

This Trojan connects to the following malicious URLs:

  • http://www.{BLOCKED}n.to/cgi-bin/prxjdg.cgi
  • http://www.{BLOCKED}sy.com/cgi-bin/prxjdg.cgi

It accesses the following websites to download files:

  • http://b.{BLOCKED}vel.biz/app.exe

It saves the files it downloads using the following names:

  • %System Root%\asetup.exe

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

Trend Micro detects the dowloaded file as:

  • WORM_RIMECUD.ZB

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

7.866.02

FIRST VSAPI PATTERN DATE:

01 Mar 2011

VSAPI OPR PATTERN File:

7.867.00

VSAPI OPR PATTERN Date:

02 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_RIMECUD.DL

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Microsoft Driver Setup = %Windows%\wjdrive32.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
    • Microsoft Driver Setup = %Windows%\wjdrive32.exe
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • {malware path and file name} = {malware path and file name}:*:%Windows%\wjdrive32.exe

Step 5

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