Analysis by: Michael Cabel
ALIASES:

Microsoft: Backdoor:Win32/IRCbot.gen!K; Symantec: W32.IRCBot

 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This backdoor may be downloaded by other malware/grayware/spyware from remote sites. It may be unknowingly downloaded by a user while visiting malicious websites.

It adds registry entries to enable its automatic execution at every system startup.

It connects to Internet Relay Chat (IRC) servers.

  TECHNICAL DETAILS

File Size: 294,912 bytes
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 15 Apr 2010

Arrival Details

This backdoor may be downloaded by other malware/grayware/spyware from remote sites.

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

Installation

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

  • %Windows%\svchost.exe

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

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

  • fgzh9xe54j0

Autostart Technique

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

HKEY_CURRENT_USER\SOFTWARE\MICROSOFT\
Windows\CURRENTVERSION\RUN
sysdiag64.exe = %Windows%\svchost.exe

HKEY_LOCAL_MACHINE\SOFTWARE\MICROSOFT\
Windows\CURRENTVERSION\RUN
MicrosoftNAPC = %Windows%\svchost.exe

HKEY_LOCAL_MACHINE\SOFTWARE\MICROSOFT\
Windows\CURRENTVERSION\Policies\
Explorer\RUN
MicrosoftCorp = %Windows%\svchost.exe

Backdoor Routine

This backdoor opens the following ports:

  • 6667

It connects to any of the following Internet Relay Chat (IRC) servers:

  • xxxxxtsghxxxxx.info

It joins any of the following IRC channel(s):

  • ##TsGh##

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 7.102.02
FIRST VSAPI PATTERN DATE: 15 Apr 2010

Step 1

For Windows ME and XP users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Identify and terminate files detected as BKDR_IRCBOT.CBC

[ Learn More ]
  1. For Windows 98 and ME users, Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. 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.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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\RUN
    • sysdiag64.exe = %Windows%\svchost.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\MICROSOFT\Windows\CURRENTVERSION\RUN
    • MicrosoftNAPC = %Windows%\svchost.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\MICROSOFT\Windows\CURRENTVERSION\Policies\Explorer\RUN
    • MicrosoftCorp = %Windows%\svchost.exe

Step 4

Scan your computer with your Trend Micro product to delete files detected as BKDR_IRCBOT.CBC 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.


Did this description help? Tell us how we did.