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BKDR_RBOT.EBR

October 08, 2012
 Analysis by: Christopher Daniel So
 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: Yes

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW


It is not capable of stealing information.

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 runs certain commands that it receives remotely from a malicious user. Doing this puts the affected computer and information found on the computer at greater risk.

It deletes itself after execution.

  TECHNICAL DETAILS

Ports:

TCP Port 113 (Authentication Service)

File Size:

93,093 bytes

File Type:

PE

File Compression:

FSG

Memory Resident:

Yes

Initial Samples Received Date:

20 Aug 2010

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%\soundblaster.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
Micr Update = "soundblaster.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Micr Update = "soundblaster.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\RunServices
Micr Update = "soundblaster.exe"

Backdoor Routine

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

  • exploited.lsass.org:19899

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

  • ##lsass#

It executes the following command(s) from a remote malicious user:

  • DCC SEND

Other Details

This backdoor does the following:

  • It receives a file from the IRC server.
  • It listens on Port 113.
  • It terminates the following processes if found running in the affected system's memory:
    • regedit.exe
    • msconfig.exe
    • netstat.exe
    • msblast.exe
    • zapro.exe
    • navw32.exe
    • navapw32.exe
    • zonealarm.exe
    • wincfg32.exe
    • PandaAVEngine.exe
    • sysinfo.exe
    • mscvb32.exe
    • MSBLAST.EXE
    • teekids.exe
    • Penis32.exe
    • bbeagle.exe
    • SysMonXP.exe
    • winupd.exe
    • winsys.exe
    • ssate.exe
    • rate.exe
    • d3dupdate.exe
    • irun4.exe

It deletes itself after execution.

  SOLUTION

Minimum Scan Engine:

8.900

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

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Micr Update=soundblaster.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Micr Update=soundblaster.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices
    • Micr Update=soundblaster.exe

Step 4

Restore this modified 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\Ole
    • From: EnableDCOM=N
      To: EnableDCOM=Y
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
    • From: restrictanonymous=1
      To: restrictanonymous=0

Step 5

Scan your computer with your Trend Micro product to delete files detected as BKDR_RBOT.EBR. 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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