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TROJ_CVE20151641.BZD

June 07, 2016
 Analysis by: Rhena Inocencio
 ALIASES:

Exploit:Win32/CVE-2015-1641 (Microsoft), Win32/Exploit.CVE-2015-1641.H (ESET), Exploit.CVE-2015-1641.Gen (F-Secure)

 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:

Via email

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

It takes advantage of software vulnerabilities in certain software to drop malicious files.

  TECHNICAL DETAILS

File Size:

1,029,412 bytes

File Type:

RTF

Memory Resident:

No

Initial Samples Received Date:

02 Jun 2016

Payload:

Drops files

Arrival Details

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

Dropping Routine

This Trojan drops the following files:

  • %Application Data%\btecache.dll
  • %All Users Profile%\svchost.dll

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.. %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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 takes advantage of unknown vulnerabilities in the following software to drop malicious files:

Other Details

This Trojan does the following:

  • It creates the following autostart registry entry to execute the dropped file:
    • HKEY_CURRENT_USER\Software\Microsoft\Office test\Special\Perf
      {Default) = "%Application Data%\btecache.dll"

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.)

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.564.07

FIRST VSAPI PATTERN DATE:

02 Jun 2016

VSAPI OPR PATTERN File:

12.565.00

VSAPI OPR PATTERN Date:

03 Jun 2016

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

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_CURRENT_USER\Software\Microsoft\Office test\Special\Perf
    • (Default) = "%Application Data%\btecache.dll"

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.

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_CVE20151641.BZD. 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 6

Download and apply this security patch Refrain from using these products until the appropriate patches have been installed. Trend Micro advises users to download critical patches upon release by vendors.


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