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WORM_IRCBOT.MBC

December 08, 2012
 Analysis by: Michael Cabel
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW


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

It connects to Internet Relay Chat (IRC) servers.

  TECHNICAL DETAILS

File Size:

114,688 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

01 Sep 2010

Arrival Details

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

  • %Application Data%\msnl.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

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

  • 8c6w4s3o9v2bw5

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Windows System Guard = "%Application Data%\msnl.exe"

Other System Modifications

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%Application Data%\msnl.exe = "%Application Data%\msnl.exe:*:Enabled:Windows System Guard"

Propagation

This worm sends the following messages using the aforementioned Instant Messaging applications:

olhar para esta foto :D
dette bildet :D
bekijk deze foto :D
schau mal das foto an :D
look at this picture :D
a :D
regardez cette photo :D
guardare quest'immagine :D
vejte se na mou fotku :D
dette billede :D
pet :D
spojrzec na to zdjecie :D
bu resmi bakmak :D
kuvaa :D
uita-te la aceasta fotografie :D
to fotografiu :D
denna bild :D
poglej to fotografijo :D
pogledaj to slike :D
seen this?? :D

It sends messages that contain links to sites hosting remote copies of itself using the following instant-messaging (IM) applications:

  • Yahoo! Messenger
  • PalTalk Messenger
  • AIM Messenger

Backdoor Routine

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

  • {BLOCKED}am.{BLOCKED}zeri.de

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

  • #newbin#

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

7.428.09

FIRST VSAPI PATTERN DATE:

01 Sep 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

Terminate a malware/grayware process

[ Learn More ]

*Note: If the detected process is not displayed in theWindows Task Manager, continue doing the next steps.

    %Application Data%\msnl.exe

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Windows System Guard = "%Application Data%\msnl.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %Application Data%\msnl.exe = "%Application Data%\msnl.exe:*:Enabled:Windows System Guard"

Step 4

Scan your computer with your Trend Micro product to delete files detected as WORM_IRCBOT.MBC. 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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