BKDR_POISON.KM

 Analysis by: Christopher Daniel So

 ALIASES:

Backdoor:Win32/Poisonivy.E (Microsoft), Backdoor.Darkmoon (Symantec), Backdoor-DKI (McAfee), Backdoor.Win32.Inject.guf (Kaspersky)

 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:

Dropped by other malware, Downloaded from the Internet

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 does not have any propagation routine.

It does not have any downloading capability.

  TECHNICAL DETAILS

File Size:

69,632 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

10 Nov 2010

Payload:

Drops files

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 drops the following copies of itself into the affected system:

  • If logged in as an administrator:
    • %System%:msxmlconfer.exe
    • %System%\msxmlconfer.exe (if dropping %System%:msxmlconfer.exe is not successful)
  • If not logged in as an administrator:
    • %User Profile%\Application Data:msxmlconfer.exe
    • %User Profile%\Application Data\msxmlconfer.exe (if dropping %User Profile%\Application Data:msxmlconfer.exe is not successful)

(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.. %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

It injects itself into the following processes running in the affected system's memory:

  • explorer.exe

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

  • KDKEK#&^%

Autostart Technique

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

HKEY_LOCAL_MACHINE\Software\Microsoft\
Active Setup\Installed Components\{5AE6AEF5-E067-B2F3-0489-98435CA721B7}
StubPath = "%System%:msxmlconfer.exe" or "%System%\msxmlconfer.exe" (if logged in as an administrator)

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{5AE6AEF5-E067-B2F3-0489-98435CA721B7} = "%User Profile%\Application Data:msxmlconfer.exe" or "%User Profile%\Application Data\msxmlconfer.exe" (if not logged in as an administrator)

Propagation

This backdoor does not have any propagation routine.

Dropping Routine

This backdoor drops the following file(s), which it uses for its keylogging routine:

  • If logged in as administrator:
    • %System%:msxmlconfer
    • %System%\msxmlconfer (if dropping %System%:msxmlconfer.exe is not successful)
  • If not logged in as administrator:
    • %User Profile%\Application Data:msxmlconfer
    • %User Profile%\Application Data\msxmlconfer (if dropping %User Profile%\Application Data:msxmlconfer.exe is not successful)

(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.. %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

Download Routine

This backdoor does not have any downloading capability.

NOTES:

Trend Micro detects the dropped file used for its keylogging routine as Mal_Xin10.

It starts a hidden default browser. It injects codes in the hidden default browser to perform its backdoor routines.

It connects to {BLOCKED}nmlgb.8800.org:80 to receive binary instructions. It then executes the binary instructions.

It does not have rootkit capabilities.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

7.640.10

FIRST VSAPI PATTERN DATE:

22 Nov 2010

VSAPI OPR PATTERN File:

7.641.00

VSAPI OPR PATTERN Date:

23 Nov 2010

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

Remove malware files dropped/downloaded by BKDR_POISON.KM

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_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {5AE6AEF5-E067-B2F3-0489-98435CA721B7} = "%User Profile%\Application Data:msxmlconfer.exe" or "%User Profile%\Application Data\msxmlconfer.exe"
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Active Setup\Installed Components\{5AE6AEF5-E067-B2F3-0489-98435CA721B7}
    • StubPath = "%System%:msxmlconfer.exe" or "%System%\msxmlconfer.exe"

Step 5

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