JS_MAILER.AC

October 09, 2012
 Analysis by: Sabrina Lei Sioting
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Propagates via email, Downloaded from the Internet

This worm may be unknowingly downloaded by a user while visiting malicious websites. It may be hosted on a website and run when a user accesses the said website.

It gathers target email addresses from the Windows Address Book (WAB).

It accesses websites to download files. This action allows this malware to possibly add other malware on the affected computer.

  TECHNICAL DETAILS

File Size:

7,078 bytes

File Type:

JS

Memory Resident:

No

Initial Samples Received Date:

13 Apr 2012

Payload:

Downloads files

Arrival Details

This worm may be unknowingly downloaded by a user while visiting malicious websites.

It may be hosted on a website and run when a user accesses the said website.

Other System Modifications

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

HKEY_CURRENT_USER\software\M0rpheuS
{default} = "Creado por .:M0rpheuS:."

HKEY_CURRENT_USER\software\OnTheFly
mailed = "1"

Propagation

This worm gathers target email addresses from the Windows Address Book (WAB).

Download Routine

This worm accesses websites to download the following files:

  • http://{BLOCKED}.146.149:102/m0rpheus/morpheus2010/m2010.php?action=SendedMails&contenido={email address}

Other Details

This worm uses the Messaging Application Programming Interface (MAPI) to send email messages with Trojan or JavaScript downloaders as attachments that bear the following details:

  • Subject: FW:Mejores Amigos!!!
  • Body: Mejoses Amigos!!!
    Asi son los amigos:)
  • Attachment: %Desktop%\Mejores Amigos.zip

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

NOTES:

This malicious JavaScript checks if an Archive file is present in the folder Mejores Amigos in the system. If found, it adds the following files to %Desktop%\Mejores Amigos.zip:

  • %Desktop%\Mejores Amigos.lnk - detected as LNK_MORPHEUS.VTG
  • %Desktop%\Informacion Importante.lnk - detected as LNK_MORPHEUS.VTG

      • It also checks if Archive files are present in the folders:

      • %Desktop%
      • %User Profile%\My Documents

      It then adds the following files to all found Archive files in the folders mentioned above:

      • %Desktop%\Mejores Amigos.lnk - detected as LNK_MORPHEUS.VTG
      • %Desktop%\Informacion Importante.lnk - detected as LNK_MORPHEUS.VTG

      It sends email messages to the target email addresses except the email addresses contain the following strings:

        {BLOCKED}sweb@hotmail.com {BLOCKED}nes58@gmail.com {BLOCKED}nes58@hotmail.com {BLOCKED}ia@mensajesmexico.com {BLOCKED}s@mensajesmexico.com {BLOCKED}rellanes@gmail.com {BLOCKED}ngullasmu@gmail.com

        It requires other components to successfully perform its intended routine.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.906.01

FIRST VSAPI PATTERN DATE:

13 Apr 2012

VSAPI OPR PATTERN File:

8.907.00

VSAPI OPR PATTERN Date:

13 Apr 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

Close all opened browser windows

Step 3

Remove malware files dropped/downloaded by JS_MAILER.AC

     LNK_MORPHEUS.VTG

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\M0rpheuS
    • @ = "Creado por .:M0rpheuS:."
  • In HKEY_CURRENT_USER\software\OnTheFly
    • mailed = "1"

Step 5

Scan your computer with your Trend Micro product to delete files detected as JS_MAILER.AC. 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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