Analysis by: Rika Joi Gregorio
ALIASES:

VirTool:Win32/CeeInject.gen!A, Trojan:Win32/Ircbrute(Microsoft), W32.Pilleuz(Norton), W32/Dorkbot.AS!tr(Fortinet), a variant of Win32/Injector.AEDM trojan(Eset)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

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

It joins an Internet Relay Chat (IRC) channel.

  TECHNICAL DETAILS

File Size: 118,329 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 30 Mar 2013
Payload: Connects to URLs/IPs, Compromises system security

Arrival Details

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

  • ev1l1lod1ld0s

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Windongs = "{malware path}\{malware file name}.exe"

Backdoor Routine

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

  • {BLOCKED}n.{BLOCKED}s.cat

It joins any of the following Internet Relay Chat (IRC) channels:

  • {BLOCKED}5

It accesses a remote Internet Relay Chat (IRC) server where it receives the following commands from a remote malicious user:

  • [Quit] - Terminate itself
  • [Help] - Print Commands
  • [Version] - Print Version
  • [Exec] - Executes shell command
  • [DLE] - Downloads and execute arbitrary file
  • [UDP] - Starts UDP Flooding
  • [OpenURL] - Opens a URL using a hidden browser
  • [SYN] - Sends a SYN Flood
  • [Stop] - Stops a spcific command
  • [Get] - Sends GET floods
  • [Post] Sends POST floods
  • [Speedtest] - check connection speed (rolotech-electronics.comuf.com, speedtest1.hivelocity.net, 68.11.12.242)

Other Details

This backdoor uses the following credentials when accessing its IRC server:

  • USERNAME: ImGay
  • NICK: zwin-{random}

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 9.826.01
FIRST VSAPI PATTERN DATE: 30 Mar 2013
VSAPI OPR PATTERN File: 9.827.00
VSAPI OPR PATTERN Date: 31 Mar 2013

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn More ]

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
    • Windongs = "{malware path}\{malware file name}.exe"

Step 4

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