EXPL_SHELLCOD.KA

September 23, 2013
 Analysis by: Anthony Joe Melgarejo
 ALIASES:

Exploit:JS/CVE-2013-3893 (Microsoft), Exploit-IE!heur !! (McAfee), HTML/Shellcode.Gen (Antivir), JS:Exploit.CVE-2013-3893.A (Bitdefender), W32/20133893.B!exploit (Fortinet), Win32/Exploit.CVE-2013-3893.A trojan (ESET)

 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:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet

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

It takes advantage of software vulnerabilities to allow a remote user or malware/grayware to download files. As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

18,434 bytes

File Type:

JS

Memory Resident:

No

Initial Samples Received Date:

21 Sep 2013

Payload:

Downloads files

Arrival Details

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

It may be downloaded from the following remote sites:

  • http://{BLOCKED}b.com/toast/html/2013-3893.html

Download Routine

This Trojan takes advantage of the following software vulnerabilities to allow a remote user or malware/grayware to download files:

After successfully exploiting the said vulnerability, this malware connects to the following URLs to possibly download other malicious files:

  • http://{BLOCKED}.{BLOCKED}.0.1/this_is_poc_code/sample.exe

It saves the files it downloads using the following names:

  • %User Temp%\runrun.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.)

As of this writing, the said sites are inaccessible.

Other Details

As of this writing, there is no available patch for this vulnerability.

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

10.290.09

FIRST VSAPI PATTERN DATE:

21 Sep 2013

VSAPI OPR PATTERN File:

10.291.00

VSAPI OPR PATTERN Date:

21 Sep 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

Search and delete these files

[ Learn More ]
There may be some 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.
  • %User Temp%\runrun.exe

Step 3

Scan your computer with your Trend Micro product to delete files detected as EXPL_SHELLCOD.KA. 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.

NOTES:

Note:

Apply the workarounds suggested by the vendor since the vulnerability does not have an available patch as of this writing.


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