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TROJ_UPATRE.YYSK

February 06, 2015
 Analysis by: Rika Joi Gregorio
 ALIASES:

Downloader.Upatre(Norton), Win32/TrojanDownloader.Waski.A trojan(Eset)

 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.

As of this writing, the said sites are inaccessible.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

24,064 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

05 Feb 2015

Payload:

Connects to URLs/IPs

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%\Umlineded.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.)

Download Routine

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

  • http://{BLOCKED}ssmoney.IN/images/rssb.jpg
  • http://{BLOCKED}a.blink.pl/fpdf/images/rrsb.jpg

It saves the files it downloads using the following names:

  • %User Temp%\PuALBbui5.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.)

As of this writing, the said sites are inaccessible.

Other Details

This Trojan deletes itself after execution.

NOTES:

This Trojan accesses http://checkip.dyndns.org/ to download and get the current IP address of the infected system. It saves the downloaded file as %User Temp%\tus5A0A.txt.

It also connects to the URL {BLOCKED.{BLOCKED}.100/0502uk12/{computername}/0/{OS Version}-{Service Pack}/0/ to send information. The following information are posted:

  • Computer name
  • Operating system version
  • Service pack installed

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

11.460.06

FIRST VSAPI PATTERN DATE:

05 Feb 2015

VSAPI OPR PATTERN File:

11.461.00

VSAPI OPR PATTERN Date:

06 Feb 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

Scan your computer with your Trend Micro product and note files detected as TROJ_UPATRE.YYSK

Step 4

Terminate a process file/s detected as TROJ_UPATRE.YYSK

[ Learn More ]

*Note: If the detected file/s is/are not displayed in theWindows Task Manager, continue doing the next steps.

Step 5

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%\PuALBbui5.exe
  • %User Temp%\tus5A0A.txt

Step 6

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