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Threat Encyclopedia

OSX_JAHLAV.B

Malware type: Others

Aliases: No Alias Found

In the wild: Yes

Destructive: No

Language: English

Platform: Mac OS X

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

Medium

Distribution potential:

Low

Description: 

To get a one-glance comprehensive view of the behavior of this malware, refer to the Behavior Diagram shown below.

OSX_JAHLAV.B Behavior Diagram

Malware Overview

Trend Micro has flagged this malware as noteworthy due to the increased potential for damage, propagation, or both, that it possesses. Specifically, it targets MAC OS X users.

This malware may be downloaded unknowingly by a user when visiting malicious Web site(s).

It may arrive on a system as a file downloaded unknowingly by a user when visiting malicious websites. The said website encourages users to download a software needed to play a video on the said site.

It arrives as a .DMG file which is a MAC OS X mountable Disk Image file. It contains a .PKG file which contains its malicious script and its component files.

Two of these files are identical malicious scripts, which are detected by Trend Micro as UNIX_JAHLAV.B.

Upon execution of this .DMG file, it displays an installation GUI entitled MacCinema. Once installation is finished, it adds certain files on the system.

In the background, while the installer is running, this malware executes certain malicious scripts. These scripts are obfuscated using SED commands and UUEncode. This script copies itself into /Library/Internet Plug-Ins/AdobeFlash and then creates a cron job that enables this malware to execute periodically every 5 minutes.

It also contains another obfuscated script. The said script contains yet another script which is detected as PERL_JAHLAV.B. This Perl script will send an HTTP GET request to a certain IP address to download another malicious Perl script. However the site is inaccessible as of this writing.

For additional information about this threat, see:

Description created: Jun. 24, 2009 11:52:13 PM GMT -0800


TECHNICAL DETAILS


File type: Other

Memory resident:  No

Size of malware: 24,299 Bytes

Initial samples received on: Mar 23, 2009

Details:

This malware may be downloaded unknowingly by a user when visiting malicious Web site(s).

It may arrive on a system as a file downloaded unknowingly by a user when visiting malicious websites. The said website encourages users to download a software needed to play a video on the said site.

It arrives as ActiveXsetup.dmg, which is a MAC OS X mountable Disk Image file. It contains a .PKG file which contains its malicious script and its component files.

Two of these files are the following identical malicious scripts, which are detected by Trend Micro as UNIX_JAHLAV.B:

  • Preinstall
  • Preupgrade

Upon execution of this .DMG file, it displays the following installation GUI entitled MacCinema:

OSX_JAHLAV.B installation

Once installation is finished, the following files are added on the system:

  • /cron.inst
  • /i386
  • /Library/Internet Plug-Ins/AdobeFlash
  • /Library/Internet Plug-Ins/Mozillaplug.plugin

In the background, while the installer is running, this malware executes the malicious scripts Install.pkg\Contents\Resources\preinstall and Install.pkg\Contents\Resources\preupgrade.

These scripts are obfuscated using SED commands and UUEncode, that, when decrypted, contains the following:

OSX_JAHLAV.B script

This script copies itself into /Library/Internet Plug-Ins/AdobeFlash and then creates a cron job that enables this malware to execute periodically every 5 minutes.

It also contains another obfuscated script:

OSX_JAHLAV.B script

The said script contains yet another script which is detected as PERL_JAHLAV.B:

OSX_JAHLAV.B script

This Perl script will send an HTTP GET request to the following IP address to download another malicious Perl script:

  • {BLOCKED}.{BLOCKED}.64.82/cgi-bin/generator.pl

However the site is inaccessible as of this writing.

This malware runs on MAC OS X.


Analysis By: Karl Dominguez


SOLUTION


Minimum scan engine version needed: 8.700

Pattern file needed: 6.221.00

Pattern release date: Jun 24, 2009


Important note: The "Minimum scan engine" refers to the earliest Trend Micro scan engine version guaranteed to detect this threat. However, Trend Micro strongly recommends that you update to the latest version in order to get comprehensive protection. Download the latest scan engine here.

Solution:

For Windows ME and XP users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

 Step 1: Search and delete this file  [learn how]

*Note: 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.

    • /cron.inst
    • /i386
    • /Library/Internet Plug-Ins/AdobeFlash
    • /Library/Internet Plug-Ins/Mozillaplug.plugin

 Step 2: Scan your computer with your Trend Micro product to delete files detected as OSX_JAHLAV.B, UNIX_JAHLAV.B, and PERL_JAHLAV.B  

*Note: 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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