Threat Encyclopedia

OSX_JAHLAV.C

Malware type: Trojan

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: 

Trend Micro has flagged this malware as noteworthy due to the increased potential for damage, propagation, or both, that it possesses.

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

OSX_JAHLAV.C Behavior Diagram

Malware Overview

This Trojan may be downloaded unknowingly by a user when visiting malicious Web sites. It may arrive as a specific file.

It comes as a MAC OS X mountable Disk Image file that contains INSTALL.PKG installer package file. The said installer package file contains its malicious script and its component files. Upon execution of this package, it displays a Graphical User Interface (GUI).

Once installation is finished, certain files are added on the system. In the background, while the installer is running, this malware executes malicious scripts.

It also contains another obfuscated script, that when deobfuscated contains yet another script, which is detected as PERL_JAHLAV.F.

This Perl script sends an HTTP GET request to an 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. 26, 2009 5:57:46 AM GMT -0800


TECHNICAL DETAILS


File type: Other

Memory resident:  No

Size of malware: 24,653 bytes

Initial samples received on: Jun 26, 2009

Details:

This Trojan may be downloaded unknowingly by a user when visiting malicious Web sites.

It may arrive on a system as the following file:

  • s-movie.dmg

It comes as a MAC OS X mountable Disk Image file that contains INSTALL.PKG installer package file.

OSX_JAHLAV.B installation

This installer package file 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.E:

  • preinstall
  • preupgrade

Executing INSTALL.PKG displays the following graphical user interface (GUI):

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 following malicious scripts:

  • Install.pkg\Contents\Resources\preinstall
  • Install.pkg\Contents\Resources\preupgrade

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

OSX_JAHLAV.B installation

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, that when deobfuscated contains yet another script, which is detected as PERL_JAHLAV.F.

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

  • {BLOCKED}.{BLOCKED}.155.38/cgi-bin/generator.pl

However the site is inaccessible as of this writing.

This Trojan runs on Windows 98, ME, NT, 2000, XP, and Server 2003.

Analysis By: Kathleen Mae Notario

Revision History:

First pattern file version: 6.230.04
First pattern file release date: Jun 26, 2009

SOLUTION


Minimum scan engine version needed: 8.700

Pattern file needed: 6.231.00

Pattern release date: Jun 27, 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 these files  [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.C, PERL_JAHLAV.F, and UNIX_JAHLAV.E  

*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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