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Worm.Win32.WANNACRY.RGN

May 03, 2024
 Analysis by: John Rainier Navato
 ALIASES:

Trojan.Ransom.WannaCryptor.H (BITDEFENDER)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Via software vulnerability

This Worm does not have any backdoor routine.

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

It does not have any information-stealing capability.

It takes advantage of certain vulnerabilities.

  TECHNICAL DETAILS

File Size:

3,723,264 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

29 Apr 2024

Payload:

Connects to URLs/IPs, Scans for open ports, , Executes files

Arrival Details

This malware arrives via the following means:

Autostart Technique

This Worm registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.0
Type = "16"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.0
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.0
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.0
ImagePath = "{initial malware file path} -m security"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.0
DisplayName = "Microsoft Security Center (2.0) Service"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.0
ObjectName = "LocalSystem"

It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\mssecsvc2.0

It starts the following services:

  • Service Name: mssecsvc2.0
    Display Name: Microsoft Security Center (2.0) Service
    Path to Executable: "{Initial Malware File Path} -m security"

Backdoor Routine

This Worm does not have any backdoor routine.

Rootkit Capabilities

This Worm does not have rootkit capabilities.

Dropping Routine

This Worm drops the following files:

It executes the dropped file. As a result, malicious routines of the dropped file are exhibited on the affected system.

Information Theft

This Worm does not have any information-stealing capability.

Other Details

This Worm does the following:

  • It connects to http://www.{BLOCKED}sodp9ifjaposdfjhgosurijfaewrwergwea.com. It is initially used as a kill switch for infection, however on this variant, it will still continue with its routine regardless of the connection.
  • It scans the following to check for open port 445:
    • Local Area Network
    • Randomly-generated IP addresses over the Internet
  • If it finds a host on the Local Area Network or the Internet with open port 445, it will attempt to exploit MS17-010 vulnerability to drop and execute a copy of itself to the remote host.
  • It uses the following file path for its dropped copies on the remote hosts.
    • %Windows%\mssecsvc.exe
  • It checks for the presence of the file %Windows%\tasksche.exe. If the file exists, it will rename the file using the following name %Windows%\qeriuwjhrf.
  • It executes %Windows%\tasksche.exe with /i parameter.

It takes advantage of the following vulnerabilities:

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

19.316.02

FIRST VSAPI PATTERN DATE:

03 May 2024

VSAPI OPR PATTERN File:

19.317.00

VSAPI OPR PATTERN Date:

04 May 2024

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 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

Remove malware/grayware files dropped/downloaded by Worm.Win32.WANNACRY.RGN. (Note: Please skip this step if the threats listed below have already been removed.)

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

Disable this malware service

[ Learn More ]
    • mssecsvc2.0

Step 6

Delete this registry key

[ 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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services
    • mssecsvc2.0

Step 7

Search and delete these files

[ 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.
  • %Windows%\tasksche.exe
  • %Windows%\mssecsvc.exe

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Worm.Win32.WANNACRY.RGN. 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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