Author: Noel Anthony Llimos   

 

Trojan.Win32.Yakes.wxoh (Kaspersky), Trojan:Win32/Tiggre!rfn (Microsoft)

 PLATFORM:

Windows

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

  • Threat Type:
    Trojan Spy

  • Destructiveness:
    No

  • Encrypted:
    Yes

  • In the wild:
    Yes

  OVERVIEW

INFECTION CHANNEL: Dropped by other malware, Downloaded from the Internet

This Trojan Spy 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: 176,640 bytes
File type: EXE
Memory resident: Yes
INITIAL SAMPLES RECEIVED DATE: 07 August 2018
PAYLOAD: Connects to URLs/IPs, Downloads files, Drops files

Arrival Details

This Trojan Spy 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 Trojan Spy drops the following copies of itself into the affected system:

  • %Program Files%\Windows NT\{random filename}.exe
      (Note: Creation of this copy is triggered when the affected system is shutting down)

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), 7 (32-bit), and 8 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), 7 (64-bit), and 8 (64-bit).)

It adds the following processes:

  • explorer.exe

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Uz{Random Hex}

It injects codes into the following process(es):

  • The created "explorer.exe" by this malware

Autostart Technique

This Trojan Spy adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random string} = "%Application Data%\{random string}.lnk"

    (Note: Creation of this registry entry is triggered when the affected system is shutting down)

Other System Modifications

This Trojan Spy adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\{Random Key}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\{random key}
(Default) = {Hex Values}

Information Theft

This Trojan Spy gathers the following data:

  • Machine Name
  • OS Information (Version, Product ID, Name, Install Date)
  • Explorer File Information
  • Volume Serial Number
  • Network Configuration (IP address, Socket, Ports)
  • Keyboard Layout

Stolen Information

This Trojan Spy sends the gathered information via HTTP POST to the following URL:

  • https://{BLOCKED}exir.com/auth/tver={value}&vcmd={value}&cc={value}&hh={hex values}&ipcnf={IP address}+&sckport={value}&pros={value}&keret={value};&email={value}

Other Details

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

  • www.google.com

It does the following:

  • It connects to the following website to send and receive information:
    • https://{BLOCKED}exir.com/auth/
    • {Random Generated Domain}.com
    • {Random Generated Domain}.net
  • It does the following:
    • Update itself
    • It does not proceed to its malicious routine if it detects that it is running in a Virtual environment
    • It deletes the cache files of Google Chrome and Mozilla Firefox
  • This malware does any of the following depending on the reply from the C&C:
    • Sleep and wait for next reply
    • Receive download URL to download other possibly malicious files
  • The file names used for its dropped copy may contain the following strings combined with random characters:
    • def
    • dns
    • exec
    • hlp
    • logon
    • mem
    • mixer
    • mon
    • pack
    • play
    • setup
    • srv
    • user
    • video
    • win
  • It may also use a purely random set of characters as filename for its dropped copy.

  SOLUTION

Minimum scan engine: 9.850
First VSAPI Pattern File: 14.426.06
First VSAPI Pattern Release Date: 06 August 2018
VSAPI OPR PATTERN-VERSION: 14.427.00
VSAPI OPR PATTERN DATE: 07 August 2018

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

[ learnMore ]

Step 4

Delete this registry key

[ learnMore ]

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\Windows\CurrentVersion\Run
    • {random string} = "%Application Data%\{random string}.lnk"
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • {Random Key}

Step 5

Delete this registry value

[ learnMore ]

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\{random key}
    • (Default) = {Hex Values}

Step 6

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.  
  • %Program Files%\Windows NT\{random filename}.exe

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TSPY_BEBLOH.YMNPV. 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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