Author: Jennifer Gumban   
 Modified By:: RonJay Kristoffer Caragay

 

Backdoor.Win32.Caphaw.aud (Kaspersky), TrojanDownloader:Win32/Upatre.AL (Microsoft)

 PLATFORM:

Windows

 OVER ALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE
Low
Medium
High
Critical

  • Threat Type:
    Backdoor

  • Destructiveness:
    No

  • Encrypted:
     

  • In the wild:
    Yes

  OVERVIEW

This backdoor 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: 118,784 bytes
File type: EXE
Memory resident: Yes
INITIAL SAMPLES RECEIVED DATE: 19 March 2014

Arrival Details

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

  • %User Temp%\pureviewer.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.)

Dropping Routine

This backdoor drops the following files:

  • %User Temp%\pure3F72.tmp
  • %User Temp%\{random filename}.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.)

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://{BLOCKED}t-solutions.com/pvt/ixusn.rtf
  • http://{BLOCKED}ck.com/mandoc/ixusn.rtf
  • http://{BLOCKED}.{BLOCKED}.131.95:{random port}/1803no21/{hostname}/{value}

  SOLUTION

Minimum scan engine: 9.750
First VSAPI Pattern File: 11.548.03
First VSAPI Pattern Release Date: 18 March 2015
VSAPI OPR PATTERN-VERSION: 11.549.00
VSAPI OPR PATTERN DATE: 19 March 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 this file

[ learnMore ]
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%\pure3F72.tmp
  • %User Temp%\{random filename}.exe

Step 4

Scan your computer with your Trend Micro product to delete files detected as BKDR_CAPHAW.XQA. 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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