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TROJ_NYMAIM.BK

April 25, 2016
 Analysis by: Jennifer Gumban
 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:

Downloaded from the Internet, Dropped by other malware


This Trojan is injected into all running processes to remain memory resident. The dropped file is injected in all running processes.

As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

655,360 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

06 Apr 2016

Payload:

Connects to URLs/IPs

Arrival Details

This Trojan may be downloaded from the following remote site(s):

  • http://www.{BLOCKED}2.com/wp-includes/images/office.exe
    • Host IP: {BLOCKED}.{BLOCKED}.104.97
    • HTML content detected as HTML_SCRINJECT.Q

Installation

This Trojan drops the following files:

  • %User Temp%\{random filename}.{random extension} - encrypted
  • %All Users Profile%\{random folder name}\{random filename}.{random extension} - encrypted

(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.. %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 is injected into all running processes to remain memory resident.

The dropped file is injected in all running processes.

Other System Modifications

This Trojan adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
{random}
{random name} = "{data}"

Download Routine

This Trojan accesses the following websites to download files:

  • http://{BLOCKED}nlpw.com/zdf3nb6i/index.php
  • http://{BLOCKED}.{BLOCKED}.195.89:80/zdf3nb6i/index.php
  • http://{BLOCKED}.{BLOCKED}.177.9:80/zdf3nb6i/index.php
  • http://{BLOCKED}.{BLOCKED}.159.179:80/zdf3nb6i/index.php

As of this writing, the said sites are inaccessible.

Other Details

This Trojan connects to the following URL(s) to check for an Internet connection:

  • google.com
  • microsoft.com

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.450.07

FIRST VSAPI PATTERN DATE:

06 Apr 2016

VSAPI OPR PATTERN File:

12.451.00

VSAPI OPR PATTERN Date:

07 Apr 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

Restart in Safe Mode

[ Learn More ]

Step 4

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_NYMAIM.BK. 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 5

The following created files/folders/registry keys/registry entries cannot be identified by the user since there are no reference values in the created key. The only way it can be identified is by comparing the present system information with a backup. Note that the said components do not have to be deleted since it won't be harmful to the system.

  • %User Temp%\{random filename}.{random extension}
  • %All Users Profile%\{random folder name}\{random filename}.{random extension}
  • HKEY_CURRENT_USER\Software\Microsoft\{random}
    • {random name} = "{data}"

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_NYMAIM.BK. 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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