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TROJ_UPATRE.YYSIA

May 05, 2015
 Analysis by: Cris Nowell Pantanilla
 ALIASES:

Trojan-Downloader.Win32.Upatre.vpj (Kaspersky)

 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:

Spammed via email

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

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:

26,112 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

27 Mar 2015

Payload:

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%\bsIjON5.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%\tep-4C1B.txt - initially contains the trojan path and filename
  • %User Temp%\temp15.pdf - normal PDF

(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 terminates the execution of the copy it initially executed and executes the copy it drops instead.

Download Routine

This Trojan accesses the following websites to download files:

  • http://{BLOCKED}.{BLOCKED}.125.167/2603uk12.pdf

It saves the files it downloads using the following names:

  • %User Temp%\tep-4C1B.txt - overwrites with the encrypted binary from URL

(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 decrypts the encrypted binary from %User Temp%\tep-4C1B.txt and drops and executes the following file:

  • %User Temp% as {letters}{2digits}.exe - detected as TROJ_UPATRE.KE

also accesses the following URLs to send information:

  • http://{BLOCKED}.{BLOCKED}.3.66:14570/2603uk12/{computername}/0/{OS Version}-{Service Pack}/0/

The following information are posted:

  • Computer name
  • Operating system version
  • Service pack installed

  SOLUTION

Minimum Scan Engine:

9.700

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

Remove the malware/grayware file that dropped/downloaded TROJ_UPATRE.YYSIA. (Note: Please skip this step if the threat(s) listed below have already been removed.)

    • TSPY_DYRE.SDER

Step 3

Identify and terminate files detected as TROJ_UPATRE.YYSIA

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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%\tep-4C1B.txt
%User Temp%\temp15.pdf

Step 5

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