Analysis by: John Anthony Banes
ALIASES:

Worm:Win32/Hamweq (Microsoft); Win32.Worm.TSD (BitDefender)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Propagates via flashdrives, Downloaded from the Internet, Dropped by other malware

This Worm arrives by connecting affected removable drives to a system. 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 drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

It executes commands from a remote malicious user, effectively compromising the affected system.

It performs denial of service (DoS) attacks on affected systems using specific flooding method(s).

  TECHNICAL DETAILS

File Size: 34,304 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 01 Aug 2018
Payload: Launches DoS/DDoS attacks, Compromises system security, Drops files, Creates files

Arrival Details

This Worm arrives by connecting affected removable drives to a system.

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 Worm drops the following copies of itself into the affected system:

  • %System Root%\RECYCLER\S-1-5-21-1482476501-1644491937-682003330-1013\win32.exe

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

It drops the following files:

  • {Drive Letter}\RECYCLER\S-1-5-21-1482476501-1644491937-682003330-1013\Desktop.ini
  • %System Root%\RECYCLER\S-1-5-21-1482476501-1644491937-682003330-1013\Desktop.ini

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

It creates the following folders:

  • %System Root%\RECYCLER\S-1-5-21-1482476501-1644491937-682003330-1013

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

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

  • asd-6+094997__

It injects codes into the following process(es):

  • explorer.exe

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{28ABC5C0-4FCB-11CF-AAX5-81CX1C635612}
StubPath = %System Root%\RECYCLER\S-1-5-21-1482476501-1644491937-682003330-1013\win32.exe

Other System Modifications

This Worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{28ABC5C0-4FCB-11CF-AAX5-81CX1C635612}

Propagation

This Worm creates the following folders in all removable drives:

  • {Drive Letter}\RECYCLER
  • {Drive Letter}\RECYCLER\S-1-5-21-1482476501-1644491937-682003330-1013

It drops the following copy(ies) of itself in all removable drives:

  • {Drive Letter}\RECYCLER\S-1-5-21-1482476501-1644491937-682003330-1013\win32.exe

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

[autorun]
open=RECYCLER\S-1-5-21-1482476501-1644491937-682003330-1013\win32.exe
icon=%SystemRoot%\system32\SHELL32.dll,4
action=Open folder to view files
shell\open=Open
shell\open\command=RECYCLER\S-1-5-21-1482476501-1644491937-682003330-1013\win32.exe
shell\open\default=1

Backdoor Routine

This Worm connects to any of the following IRC server(s):

  • aa.{BLOCKED}ere.biz
  • aa.{BLOCKED}nad.com

It executes the following commands from a remote malicious user:

  • Download and execute files
  • Perform flooding attacks

As of this writing, the said servers are currently inaccessible.

Denial of Service (DoS) Attack

This Worm performs denial of service (DoS) attacks on affected systems using the following flooding method(s):

  • UDP Flood
  • SYN Flood

Other Details

This Worm does the following:

  • This worm sends a message to its server once successfully propagate through removable drives with the following format:
    • PRIVMSG #newusb :Infected usb drive: {drive letter}:

It uses the following credentials when accessing its IRC server:

  • PASS trb
    NICK {random string 1}
    USER {random string 2} "" "{random string 3}" :{random string 2}

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.418.03
FIRST VSAPI PATTERN DATE: 02 Aug 2018
VSAPI OPR PATTERN File: 14.419.00
VSAPI OPR PATTERN Date: 03 Aug 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

[ 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_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{28ABC5C0-4FCB-11CF-AAX5-81CX1C635612}
    • StubPath = %System Root%\RECYCLER\S-1-5-21-1482476501-1644491937-682003330-1013\win32.exe

Step 5

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components
    • {28ABC5C0-4FCB-11CF-AAX5-81CX1C635612}

Step 6

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • {Drive Letter}\RECYCLER
  • {Drive Letter}\RECYCLER\S-1-5-21-1482476501-1644491937-682003330-1013
  • %System Root%\RECYCLER\S-1-5-21-1482476501-1644491937-682003330-1013

Step 7

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.
  • {Drive Letter}\RECYCLER\S-1-5-21-1482476501-1644491937-682003330-1013\Desktop.ini
  • %System Root%\RECYCLER\S-1-5-21-1482476501-1644491937-682003330-1013\Desktop.ini

Step 8

Search and delete AUTORUN.INF files created by WORM_HAMWEQ.NZU that contain these strings

[ Learn More ]
  • [autorun]
  • open=RECYCLER\S-1-5-21-1482476501-1644491937-682003330-1013\win32.exe
  • icon=%SystemRoot%\system32\SHELL32.dll,4
  • action=Open folder to view files
  • shell\open=Open
  • shell\open\command=RECYCLER\S-1-5-21-1482476501-1644491937-682003330-1013\win32.exe
  • shell\open\default=1

Step 9

Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_HAMWEQ.NZU. 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 10

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.

RESTORE
  • Close Registry Editor.


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