Analysis by: Rhena Inocencio
ALIASES:

Exploit.Java.CVE-2013-2423.a (Kaspersky), a variant of Java/Exploit.CVE-2013-2423.B trojan (NOD32)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 OVERALL RISK RATING:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This Trojan executes when a user accesses certain websites where it is hosted.

  TECHNICAL DETAILS

File Size: Varies
File Type: JAR
Initial Samples Received Date: 29 Apr 2013

Arrival Details

This Trojan executes when a user accesses certain websites where it is hosted.

Download Routine

This Trojan saves the files it downloads using the following names:

  • %User Temp%\j.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It downloads a possibly malicious file from a certain URL. The URL where this malware downloads the said file depends on the following parameter(s) passed on to it by its components:

  • lewd

NOTES:

It checks if the system language is EN (english) and then checks for the operating system.

It drops the following autostart components:

  • %All Users Profile%\Start Menu\Program\Startup\j.bat
  • %Application Data%\Microsoft\Windows\Start Menu\Programs\Startup\j.bat

The dropped file J.BAT contains the following:

  • cmd /c start %User Temp%\j.exe

It exploits the following vulnerability to bypass permission checks and disable security manager:

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 9.886.03
FIRST VSAPI PATTERN DATE: 29 Apr 2013

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Close all opened browser windows

Step 3

Scan your computer with your Trend Micro product to delete files detected as JAVA_LAMAR.AB. 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.

Step 4

Download and apply this security patch Refrain from using these products until the appropriate patches have been installed. Trend Micro advises users to download critical patches upon release by vendors.


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