Analysis by: Jemimah Mae Molina

ALIASES:

Trojan.Win32.Yakes.ygsx (Kaspersky) ; a variant of Win32/GenKryptik.CTVG trojan (Microsoft)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Trojan Spy

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware, Spammed via email

This Trojan Spy arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It downloads a file from a certain URL then renames it before storing it in the affected system.

It retrieves specific information from the affected system.

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size: 872,448 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 28 Feb 2019
Payload: Connects to URLs/IPs, Steals information, Compromises system security

Arrival Details

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

It 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 files:

  • {malware directory}/{malware file name}.inf - part of its auto-start mechanism

It adds the following processes:

  • {malware directory}/{malware file name}.exe --vwyxz
  • svchost.exe

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

  • ServiceEntryPointThread

It injects codes into the following process(es):

  • svchost.exe

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
IEAK\GroupPolicy\PendingGPOs
Count = 4

HKEY_CURRENT_USER\Software\Microsoft\
IEAK\GroupPolicy\PendingGPOs
Path1 = "{malware directory}/{malware file name}.inf"

HKEY_CURRENT_USER\Software\Microsoft\
IEAK\GroupPolicy\PendingGPOs
Section1 = "DefaultInstall"

Other System Modifications

This Trojan Spy adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\AppDataLow
{random value}_0 = "HEX VALUES"

HKEY_CURRENT_USER\Software\AppDataLow
{random value}_1 = "HEX VALUES"

HKEY_CURRENT_USER\Software\AppDataLow
{random value}_2 = "HEX VALUES"

HKEY_CURRENT_USER\Software\AppDataLow
{random value}_3 = "HEX VALUES"

HKEY_CURRENT_USER\Software\AppDataLow
{random value}_4 = "HEX VALUES"

HKEY_CURRENT_USER\Software\AppDataLow
{random value}_5 = "HEX VALUES"

HKEY_CURRENT_USER\Software\AppDataLow
{random value}_6 = "HEX VALUES"

HKEY_CURRENT_USER\Software\AppDataLow
{random value}_7 = "HEX VALUES"

HKEY_CURRENT_USER\Software\Microsoft
{GUID}_1 = "HEX VALUES"

HKEY_CURRENT_USER\Software\Microsoft
{GUID}_2 = "HEX VALUES"

HKEY_CURRENT_USER\Software\Microsoft
{GUID}_3 = "HEX VALUES"

Download Routine

This Trojan Spy downloads files from the following URLs then renames them before storage in the affected system:

  • {BLOCKED}l.online/rpersist4/msiexec.exe

Information Theft

This Trojan Spy retrieves the following information from the affected system:

  • CPU information
  • Memory Information (RAM)
  • Network Configuration
  • UserName
  • ComputerName
  • Keyboard activity (keylogging)
  • ScreenCapture

Other Details

This Trojan Spy connects to the following website to send and receive information:

  • {BLOCKED}arde.host

It does the following:

  • It has the following capabilities:
    • Download file from its C&C
    • Monitor web browsing activities (HTTP and HTTPS) via proxy on port 6000
    • Load additional modules to perform other malicious behavior, such as:
      • Keylogging
      • Modify proxy settings
      • Screen Capture
  • It has several anti-analysis techniques, such as:
    • Checks the string "Xeon" at HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\CentralProcess\0\ProcessorNameString
    • Searches for any of the following loaded module:
      • dbghelp.dll
      • sbiedll.dll
    • Cross-check the UserName with the following:
      • CurrentUser
      • Sandbox
      • xqnuwino
    • Cross-check the ComputerName with the following:
      • SANDBOX
      • 7SILVIA
    • Checks the registry key HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System for the following string value
      • AMI
      • BOCHS
      • VBOX
      • QEMU
      • SMCI
      • INTEL – 6040000
      • FTNT-1
      • SONI
    • Checks the registry key HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\VideoBiosVersion for the following string value
      • VirtualBox
    • Checks the registry key HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\SystemBiosVersion for the following string value
      • "55274-640-2673064-23950"
      • "76487-644-3177037-23510"
      • "76487-337-8429955-22614"
  • It accepts the following arguments:
    • --vwxyz: executes malware's main routine
    • --reinstall: restarts itself
    • --service: creates a new environment variable called "USERNAME_REQUIRED" and sets it to "TRUE"
    • -test: terminates itself
  • It checks for the following environment variable to skip anti-sandbox and anti-analysis:
    • crackmeololo

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.864.04
FIRST VSAPI PATTERN DATE: 11 Mar 2019
VSAPI OPR PATTERN File: 14.865.00
VSAPI OPR PATTERN Date: 12 Mar 2019

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

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\IEAK\GroupPolicy\PendingGPOs
    • Count = 4
  • In HKEY_CURRENT_USER\Software\Microsoft\IEAK\GroupPolicy\PendingGPOs
    • Path1 = "{malware directory}/{malware file name}.inf"
  • In HKEY_CURRENT_USER\Software\Microsoft\IEAK\GroupPolicy\PendingGPOs
    • Section1 = "DefaultInstall"
  • In HKEY_CURRENT_USER\Software\AppDataLow
    • {random value}_0 = "HEX VALUES"
  • In HKEY_CURRENT_USER\Software\AppDataLow
    • {random value}_1 = "HEX VALUES"
  • In HKEY_CURRENT_USER\Software\AppDataLow
    • {random value}_2 = "HEX VALUES"
  • In HKEY_CURRENT_USER\Software\AppDataLow
    • {random value}_3 = "HEX VALUES"
  • In HKEY_CURRENT_USER\Software\AppDataLow
    • {random value}_4 = "HEX VALUES"
  • In HKEY_CURRENT_USER\Software\AppDataLow
    • {random value}_5 = "HEX VALUES"
  • In HKEY_CURRENT_USER\Software\AppDataLow
    • {random value}_6 = "HEX VALUES"
  • In HKEY_CURRENT_USER\Software\AppDataLow
    • {random value}_7 = "HEX VALUES"
  • In HKEY_CURRENT_USER\Software\Microsoft
    • {GUID}_1 = "HEX VALUES"
  • In HKEY_CURRENT_USER\Software\Microsoft
    • {GUID}_2 = "HEX VALUES"
  • In HKEY_CURRENT_USER\Software\Microsoft
    • {GUID}_3 = "HEX VALUES"

Step 5

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.
  • {malware directory}/{malware file name}.inf

Step 6

Reset Internet privacy settings

[ Learn More ]

Step 7

Reset Internet security settings

[ Learn More ]

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TrojanSpy.Win32.GOOTKIT.AB. 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 9

Scan your computer with your Trend Micro product to delete files detected as TrojanSpy.Win32.GOOTKIT.AB. 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 the following Trend Micro Support pages for more information:


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