Analysis by: Adrian Cofreros
ALIASES:

TrojanDropper:Win32/Gupdamon.A (Microsoft)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet

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.

  TECHNICAL DETAILS

File Size: 464,451 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 04 Nov 2014
Payload: Drops files

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.

Installation

This Trojan drops the following files:

  • %User Temp%\outside.gif
  • %User Temp%\sf.png
  • %User Temp%\help.lnk <- a shortcut that will rename outside.gif to outside.js
  • %User Temp%\Shipping_Invoice.pdf <-non-malicious pdf file
  • %User Temp%\outside.js <- creates a copy of sf.png and modify it to be save as sf.exe
  • %User Temp%\sf.exe <-modified copy of sf.png
  • %User Temp%\inside.js <-executes ab.exe
  • %User Temp%\ab.exe <- detected as BKDR_ANDROM.OL

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 11.214.01
FIRST VSAPI PATTERN DATE: 15 Oct 2014
VSAPI OPR PATTERN File: 11.215.00
VSAPI OPR PATTERN Date: 16 Oct 2014

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 this file

[ 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%\outside.gif
  • %User Temp%\sf.png
  • %User Temp%\help.lnk
  • %User Temp%\Shipping_Invoice.pdf
  • %User Temp%\outside.js
  • %User Temp%\sf.exe
  • %User Temp%\inside.js
  • %User Temp%\ab.exe

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_GUPDA.OL. 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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