Analysis by: Michelle Morales
ALIASES:

TrojanDownloader:Win32/Upatre (Microsoft); Downloader.Upatre (Symantec); Troj/Dyreza-BK (Sophos); Win32/TrojanDownloader.Waski.F (ESET)

 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, Spammed via email

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

It does not have any propagation routine.

It does not have any backdoor routine.

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

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: 27,136 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 01 Feb 2015
Payload: Connects to URLs/IPs, Downloads files

Arrival Details

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

Installation

This Trojan drops the following copies of itself into the affected system and executes them:

  • %User Temp%\document.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 drops the following files:

  • %User Temp%\adob8864.txt ← contains the initially executed malware path, which is overwritten once it downloads

(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.)

File Infection

This Trojan adds the following registry entries that act as infection markers:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion
marker_gjru_fbegrihlgm = "TRUE"

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Download Routine

This Trojan accesses the following websites to download files:

  • www.{BLOCKED}utions.com/files/manualac.pdf
  • {BLOCKED}oteknologi.co.id/fonts/manualac.pdf

It saves the files it downloads using the following names:

  • %User Temp%\adob8864.txt

(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.

Other Details

This Trojan deletes the initially executed copy of itself

NOTES:

This Trojan decompresses the binary code from %User Temp%\adob8864.txt. The decompressed binary code results to the executable file %User Temp%\{6letters}{1digit}.exe, which is detected as TSPY_DYRE.SMAB. The executable is then executed by this malware.

It connects to the following URLs to report infection of the affected system:

  • {BLOCKED}.{BLOCKED}.242.226:{port}/2901us21/{Computer Name of the affected system}/{OS Version}/0/
  • {BLOCKED}.{BLOCKED}.242.226:{port}/2901us21/{Computer Name of the affected system}/1/0/0

It reports the following information:

  • Computer Name
  • Operating system version
  • Service Pack

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 11.446.02
FIRST VSAPI PATTERN DATE: 29 Jan 2015
VSAPI OPR PATTERN File: 11.447.00
VSAPI OPR PATTERN Date: 30 Jan 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

Remove malware/grayware files dropped/downloaded by TROJ_UPATRE.YYSG. (Note: Please skip this step if the threats listed below have already been removed.)

    • TSPY_DYRE.SMAB

Step 4

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%\adob8864.txt

Step 5

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion
    • marker_gjru_fbegrihlgm = "TRUE"

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_UPATRE.YYSG. 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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