Analysis by: Sabrina Lei Sioting
ALIASES:

Backdoor.PHP.Pbot [Ikarus]; Heuristic.BehavesLike.JS.Suspicious.G [McAfee]; Backdoor:PHP/IRCbot.F [Microsoft]

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet

This backdoor may be hosted on a website and run when a user accesses the said website.

It executes commands from a remote malicious user, effectively compromising the affected system.

As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: 16,589 bytes
File Type: Script
Memory Resident: No
Initial Samples Received Date: 31 Mar 2012
Payload: Downloads files, Compromises system security

Arrival Details

This backdoor may be hosted on a website and run when a user accesses the said website.

Backdoor Routine

This backdoor opens the following port(s) where it listens for remote commands:

  • 23232

It connects to any of the following IRC server(s):

  • {BLOCKED}gels-agency.nl

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

  • #wWw#

It executes the following commands from a remote malicious user:

  • Change nickname
  • Download files
  • Execute an application
  • Exit connection
  • Launch UDP flooding method
  • Logout connection
  • Restart connection
  • Switch server

Download Routine

This backdoor connects to the following URL(s) to download its component file(s):

  • http://{BLOCKED}.host/file

It saves the files it downloads using the following names:

  • /tmp/file

As of this writing, the said sites are inaccessible.

NOTES:
It sets the permission of the downloaded file to Read, Write, and Executable.

  SOLUTION

Minimum Scan Engine: 9.200
VSAPI OPR PATTERN File: 8.877.00
VSAPI OPR PATTERN Date: 31 Mar 2012

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

Close all opened browser windows

Step 3

Scan your computer with your Trend Micro product to delete files detected as PHP_IRCBOT.EVL. 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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