Analysis by: Mark Joseph Manahan
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Spammed via email

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

It may also compose messages that can be part of its spamming routine.

It executes downloaded files whose malicious routines are exhibited by the affected system. As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: Varies
File Type: EXE, DLL
File Compression: MEW
Memory Resident: Yes
Initial Samples Received Date: 21 Jun 2012
Payload: Downloads files, Steals information

Arrival Details

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

Installation

This worm drops the following files:

  • %Windows%\tserv.exe - also detected as WORM_STRAT.MJ
  • %System%\MSJI449C14B7.DLL - also detected as WORM_STRAT.MJ
  • %System%\CMUT449C14B7.DLL - also detected as WORM_STRAT.MJ
  • %System%\HPZL449C14B7.EXE - also detected as WORM_STRAT.MJ
  • %Windows%\tserv.dll - also detected as WORM_STRAT.MJ
  • %System%\e1.dll - also detected as WORM_STRAT.MJ
  • %Windows%\tserv.wax - contains e-mail addresses obtained from infected machine
  • %Windows%\tserv.dat - non-malicious
  • %Windows%\tserv.z - non-malicious
  • {Malware Path}\{random number}.tmp - Garbage text opened by notepad to deceive the victim.

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.. %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.)

It injects codes into the following process(es):

  • nod32krn
  • avginet
  • avgupsvc
  • kavsvc
  • upgrader
  • drwebupw
  • spiderml
  • autodown
  • kav
  • mcupdate
  • tbmon
  • wuauclt
  • wuauclt1
  • wupdmgr

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
tserv = "%Windows%\tserv.exe s"

It modifies the following registry entry(ies) to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Windows
AppInit_DLLs = "msji449c14b7.dll e1.dll"

(Note: The default value data of the said registry entry is {blank}.)

Propagation

This worm gathers target email addresses from files with the following extensions:

  • adb
  • asp
  • cfg
  • cgi
  • dbx
  • eml
  • htm
  • jsp
  • mbx
  • mdx
  • mht
  • mmf
  • msg
  • nch
  • ods
  • php
  • sht
  • stm
  • tbb
  • txt
  • uin
  • wab
  • wsh
  • xml

It may also compose messages that can be part of its spamming routine.

Download Routine

This worm connects to the following website(s) to download and execute a malicious file:

  • http://www4.{BLOCKED}njerinkas.com/chr/wtb/lt.exe

It saves the files it downloads using the following names:

  • %Temp%\~{random number}.tmp

(Note: %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp or C:\WINNT\Temp.)

It executes downloaded files :

  • %Temp%\~{random number}.tmp - contains massmailing routine

(Note: %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp or C:\WINNT\Temp.)

whose malicious routines are exhibited by the affected system.

As of this writing, the said sites are inaccessible.

Information Theft

This worm gathers the following data:

  • Operating System Type
  • Operating System Version

Stolen Information

This worm sends the gathered information via HTTP POST to the following URL:

  • www3.{BLOCKED}njerinkas.com/cgi-bin/pr.cgi

NOTES:
The worm deletes the downloaded file after execution.

  SOLUTION

Minimum Scan Engine: 9.200
VSAPI OPR PATTERN File: 9.229.00
VSAPI OPR PATTERN Date: 02 Jul 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 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\Windows\CurrentVersion\Run
    • tserv = "%Windows%\tserv.exe s"

Step 4

Restore this modified registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator’s help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows]
    • From: AppInit_DLLs = "msji449c14b7.dll e1.dll"
      To: AppInit_DLLs =   "{blank}" 

Step 5

Search and delete these files

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %Windows%\tserv.wax
  • %Windows%\tserv.da
  • %Windows%\tserv.z
  • {Malware Path}\{random number}.tmp
  • %Temp%\~{random number}.tmp

Step 6

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