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HTML_EXPLOYT.THAAHH

August 23, 2018
 Analysis by: Noel Anthony Llimos
 ALIASES:

JS/Exploit.q (McAfee), JS/Agent.NNR!tr (Fortinet)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites. It may be hosted on a website and run when a user accesses the said website.

  TECHNICAL DETAILS

File Size:

96,751 bytes

Memory Resident:

No

Initial Samples Received Date:

17 Jan 2018

Payload:

Drops files, Downloads files, Connects to URLs/IPs

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

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

Installation

This Trojan drops the following files:

  • %User Temp%\System32\shell32.dll detected as ← TROJ_STARTER.THBGBH

(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, 7, and 8.)

It creates the following folders:

  • %User Temp%\System32

(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, 7, and 8.)

Download Routine

This Trojan connects to the following website(s) to download and execute a malicious file:

  • http://{BLOCKED}.{BLOCKED}.60.18/?NDY2MjUz&YGcekzkoSzY&aIAZTzw=bWlzc2luZw==&DYazViGTZnQ=bG9jYXRlZA==&evRdtGXw=Y2FwaXRhbA==&vwezWX=YXR0YWNrcw==&qYlYxE=YXR0YWNrcw==&cWtHzRvHTFPQDK=YXR0YWNrcw==&LyObIiBqgc=dW5rbm93bg==&ICdAGwhETKUW=bG9jYXRlZA==&LjUehzEDyO=YXR0YWNrcw==&YQHXJgt=YXR0YWNrcw==&Lsfgd=wHjQMvXcJwDMFYbGMvrESqNbNknQA0KPxpH2_drSdZqxKGni1eb5UUSk6FiCEh3h96Yo&dciyJbezS=bG9jYXRlZA==&kiXXUr=bWlzc2luZw==&zTFEayfExgesp=bG9jYXRlZA==&cKSCrpJViuQfh=dW5rbm93bg==&zvYkEDwaWNM=bWlzc2luZw==&kQjmBbOTr=bWlzc2luZw==&ymPsdP3=fOBYP1GzixDWeAFjlYtfUghA8Kuq2kLVwUSYhJPQrBeMYg919pucHbg_0VT8_-xUdMgX&QkHytjPAmFYY=dW5rbm93bg==

It saves the files it downloads using the following names:

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.912.02

FIRST VSAPI PATTERN DATE:

18 Jan 2018

VSAPI OPR PATTERN File:

13.913.00

VSAPI OPR PATTERN Date:

19 Jan 2018

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

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%\{Random Characters}.exe ← Detected as TROJ_RAMNIT.CBQ
  • %User Temp%\System32\shell32.dll detected as ← TROJ_STARTER.THBGBH

Step 4

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %User Temp%\System32

Step 5

Close all opened browser windows

Step 6

Scan your computer with your Trend Micro product to delete files detected as HTML_EXPLOYT.THAAHH. 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 the following Trend Micro Support pages for more information:


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