Analysis by: Roland Marco Dela Paz
ALIASES:

Backdoor.Meciv (Symantec); Backdoor:Win32/Meciv.A (Microsoft)

 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 may be dropped by other malware.

It connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size: Varies
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 25 Feb 2012
Payload: Compromises system security, Connects to URLs/IPs, Drops files

Arrival Details

This backdoor may be dropped by the following malware:

  • TROJ_ARTIEF.LN

Installation

This backdoor drops the following files:

  • %System%\adsmsexy.dll - also detected as BKDR_MECIV.LN
  • %System%\datac1en.dll - also detected as BKDR_MECIV.LN

(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.)

Its DLL component is injected to the following process(es):

  • svchost.exe

It creates the following folders:

  • %System Root%\Documents and Settings\NetworkService\Local Settings\Application Data\Microsoft Office Update

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

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

  • LINLINLVMAN

Autostart Technique

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WmdmPmSN\Parameters
ServiceStartAddr = {malware path and file name}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WmdmPmSp\Parameters
ServiceDll = %System%\datac1en.dll

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WmdmPmSN\Parameters
ServiceDll = %System%\adsmsexy.dll

(Note: The default value data of the said registry entry is %System%\mspmsnsv.dll .)

Other System Modifications

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

HKEY_USERS\.DEFAULT\Software\
Microsoft\Windows\CurrentVersion\
Internet Settings
ProxyEnable = 0

Backdoor Routine

This backdoor connects to the following websites to send and receive information:

  • {BLOCKED}p.{BLOCKED}l.com
  • {BLOCKED}e.{BLOCKED}l-temp.com

NOTES:
It sends the following information to its C&C server:

  • Hostname
  • MAC address
  • IP address
  • Operating System
  • Codepage
  • Locale
  • File name of the malicious executable
  • Campaign name
  • If a file named sys32time.ini exists and if its size is greater than or equal to 1MB Y/N
  • If a file named ipop.dll exists Y/N
  • Malware version

It is capable of executing the following commands:

  • Download file(s)
  • Upload file(s)
  • Delete file(s)
  • Move file(s)
  • List files from a specific directory
  • Create a directory
  • Terminate process(es)
  • Execute DOS commands
  • Execute a specific file

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 08.800.05
FIRST VSAPI PATTERN DATE: 26 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

Remove malware files dropped/downloaded by BKDR_MECIV.LN

    •  TROJ_ARTIEF.LN

Step 3

Scan your computer with your Trend Micro product and note files detected as BKDR_MECIV.LN

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result. %System Root%\Documents and Settings\NetworkService\Local Settings\Application Data\Microsoft Office Update

Step 6

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\SYSTEM\CurrentControlSet\Services\WmdmPmSN\Parameters
    • ServiceStartAddr = {malware path and file name}
  • In HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • ProxyEnable = 0

Step 7

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\SYSTEM\CurrentControlSet\Services\WmdmPmSN\Parameters
    • From: ServiceDll = %System%\adsmsexy.dll
      To: ServiceDll = %System%\mspmsnsv.dll

Step 8

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.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • WmdmPmSp

Step 9

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