Analysis by: Janus Agcaoili
ALIASES:

TrojanDownloader:X97M/Donoff (Microsoft), Trojan-Downloader.VBS.Agent.azg (Kaspersky), X97M.DownLoader.90 (DrWeb)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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 accesses websites to download files. This action allows this malware to possibly add other malware on the affected computer. It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size: 92,672 bytes
File Type: XLS
Initial Samples Received Date: 02 Dec 2015

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.

Download Routine

This Trojan accesses websites to download the following files:

  • {BLOCKED}-89.ru/4367yt/p0o6543f.exe
  • {BLOCKED}-89.ru/cgi-sys/suspendedpage.cgi

It saves the files it downloads using the following names:

  • %User Temp%\.exe

(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.)

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.186.05
FIRST VSAPI PATTERN DATE: 02 Dec 2015
VSAPI OPR PATTERN File: 12.187.00
VSAPI OPR PATTERN Date: 03 Dec 2015

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%\.exe

Step 4

Scan your computer with your Trend Micro product to delete files detected as X2KM_DRIDEX.YYSPI. 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 5

Enable the macro virus protection in Microsoft Office Applications

[ Learn More ]


Did this description help? Tell us how we did.