Analysis by: Rhena Inocencio
ALIASES:

Trojan:Win32/Ircbrute (Microsoft), W32.Spybot.Worm (Symantec), RDN/Generic Downloader.x!bx (McAfee)

 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: No

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

  TECHNICAL DETAILS

File Size: 43,008 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 06 Mar 2013
Payload: Compromises system security, Connects to URLs/IPs

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.

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
Winpxe = "{Malware Path and Filename}"

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • udp: Start UDP flood
  • syn: Send SYN flood
  • exec: Perform remote shell
  • openurl: Open URL in a hidden browser
  • version: Print bot version
  • speedtest: Perform speed test
  • stop: Stop specific thread
  • quit: Terminate itself
  • dle: Download and execute a file (parameter: {URL} {filename for saving} {to execute (1) or not (0)})

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • 199.229.249.189:443

Other Details

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

  • NICK: zwin-{random value}|{random number}|

NOTES:

This backdoor joins an IRC server where it sends and receives its backdoor commands:

  • ddos.cat IRC Network

It connects to the following site to perform a speed test:

  • http://speedtest1.hivelocity.net/speedtest/upload.php?x={random value}

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 9.768.07
FIRST VSAPI PATTERN DATE: 06 Mar 2013
VSAPI OPR PATTERN File: 9.769.00
VSAPI OPR PATTERN Date: 07 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

Scan your computer with your Trend Micro product and note files detected as BKDR_IRCBOT.MEO

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
    • Winpxe = "{Malware Path and Filename}"

Step 5

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