BKDR_ZOMBIE.SM

June 23, 2011
 Analysis by: Roland Marco Dela Paz
 Modified by: Sabrina Lei Sioting
 ALIASES:

Trojan:Win32/Lukicsel.J (Microsoft), Backdoor.MSIL.IrcBot.mq (Kaspersky), Backdoor.IRC.Zlulbot (Symantec), W32/Sdbot.worm!lg (McAfee), TR/Lukicsel.J.2 (Antivir), W32/ZOMBIE.SM!tr.bdr (Fortinet), Backdoor.MSIL (Ikarus),

 PLATFORM:

Windows 2000, Windows XP, Server 2003

 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

This malware is believed to be the bot used by a hacking group that perpetrated attacks against Brazilian websites.

To get a one-glance comprehensive view of the behavior of this Backdoor, refer to the Threat Diagram shown below.

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 connects to Internet Relay Chat (IRC) servers. It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size:

110,592 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

23 Jun 2011

Payload:

Connects to URLs/IPs, Compromises system security, Drops files

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:

  • %System%\svchosth.exe or %System%\svchosta.exe or %System%\svchostzx.exe or %System%\svchoste.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

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
svchostn.exe = ""%System%\{malware file name}" start4dalife"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
svchostn.exe = ""%System%\{malware name}" start4alife""

Backdoor Routine

This backdoor opens the following ports:

  • 6697
  • 6667

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

  • irc.{BLOCKED}.li
  • irc.{BLOCKED}.net

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

  • #DL34k3rBn3t
  • #secAssgdf

It executes the following commands from a remote malicious user:

  • attack - perform Denial of Service (DOS) attack to target site/IP
  • stop - stop Denial of Service (DOS) attack
  • stopall - stop Denial of Service (DOS) attack and terminate itself
  • update - update copy of itself
  • info - gather and send the following information to the server:
    • IP Address
    • Machine Name
    • Domain
    • Username
    • Operating System
    • Working Set
    • Common Language Runtime (CLR) Version
  • status - display status of current attack being performed by the bot
  • getkl - gather and send keystroked informtion to the server

NOTES:
It saves the downloaded updated copy of itself as:

  • %System%\svchosth.exe
It connects to the following URL(s) to get the affected system's external IP address:
  • http://myip.ozymo.com/
It uses any of the following IRC nick(s):
  • B{random}
It uses any of the following IRC password(s):
  • TxRx0192

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

8.242.06

FIRST VSAPI PATTERN DATE:

23 Jun 2011

VSAPI OPR PATTERN File:

8.243.00

VSAPI OPR PATTERN Date:

23 Jun 2011

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

Identify and terminate files detected as BKDR_ZOMBIE.SM

[ Learn More ]
  1. 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.
  2. 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
    • svchostn.exe = ""%System%\{malware name}" start4dalife"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • svchostn.exe = ""%System%\{malware name}" start4alife""

Step 4

Scan your computer with your Trend Micro product to delete files detected as BKDR_ZOMBIE.SM. 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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