Analysis by: Sabrina Lei Sioting
 Modified by: Kathleen Notario
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: 49,152 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 23 Feb 2012

Arrival Details

This backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

It 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\
Active Setup\Installed Components\{9E41174A-B99F-F49D-5CD0-0EF87DF3A162}
StubPath = "%System%:msjbvpncon.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{0082ABF9-9309-614B-C2DD-C00CC33A8073}
StubPath = "%System%:mssendfull.exe"

Other System Modifications

This backdoor adds the following registry keys as part of its installation routine:

HKEY_CURRENT_USER\Software\Local AppWizard-Generated Applications

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{9E41174A-B99F-F49D-5CD0-0EF87DF3A162}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{0082ABF9-9309-614B-C2DD-C00CC33A8073}

Backdoor Routine

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

  • jp.{BLOCKED}n.com
  • tw.{BLOCKED}arleft.com

Other Details

This backdoor deletes the initially executed copy of itself

NOTES:

It drops a copy of itself as an Alternate Date Stream:

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

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.796.05
FIRST VSAPI PATTERN DATE: 23 Feb 2012
VSAPI OPR PATTERN File: 8.797.00
VSAPI OPR PATTERN Date: 24 Feb 2012

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 key

[ 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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_CURRENT_USER\Software
    • Local AppWizard-Generated Applications
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components
    • {9E41174A-B99F-F49D-5CD0-0EF87DF3A162}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components
    • {0082ABF9-9309-614B-C2DD-C00CC33A8073}

Step 4

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

NOTES:

To delete the Alternate Data Stream:

  1. Download streams.exe from http://technet.microsoft.com/en-us/sysinternals/bb897440
  2. Open a command prompt. To do this, click Start>Run, type cmd.exe in the text box provided, then press Enter.
  3. Go to the directory where you saved streams.exe and type:
    streams -d %System%


Did this description help? Tell us how we did.