WORM_HAMWEQ.AIJ
Worm:Win32/Hamweq.A (Microsoft); W32/Hamweq.worm.aj (McAfee); Backdoor.Hamweq.B (BitDefender); Trojan.Win32.Buzus.hizi (Kaspersky)
Windows
Threat Type: Worm
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
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
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 non-malicious files:
- %System Root%\RESTORE\S-1-5-21-1482476501-1644491937-682003330-1013\Desktop.ini
- {Drive Letter}:\RESTORE\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 drops the following copies of itself into the affected system:
- %System Root%\RESTORE\S-1-5-21-1482476501-1644491937-682003330-1013\Taquito.exe
(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%\RESTORE
- %System Root%\RESTORE\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:
- VrX-1+2_6
It injects itself into the following processes as part of its memory residency routine:
- 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-33CF-AAX5-35GX1C642122}
StubPath = "%System Root%\RESTORE\S-1-5-21-1482476501-1644491937-682003330-1013\Taquito.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Internet Security Services = "%System Root%\RESTORE\S-1-5-21-1482476501-1644491937-682003330-1013\Taquito.exe"
Propagation
This worm creates the following folders in all removable drives:
- {Drive Letter}:\RESTORE
- {Drive Letter}:\RESTORE\S-1-5-21-1482476501-1644491937-682003330-1013
It drops the following copy(ies) of itself in all removable drives:
- {Drive Letter}:\RESTORE\S-1-5-21-1482476501-1644491937-682003330-1013\Taquito.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=RESTORE\S-1-5-21-1482476501-1644491937-682003330-1013\Taquito.exe
icon=%SystemRoot%\system32\SHELL32.dll,4
action=Open folder to view files
shell\open=Open
shell\open\command=RESTORE\S-1-5-21-1482476501-1644491937-682003330-1013\Taquito.exe
shell\open\default=1
Backdoor Routine
This worm connects to any of the following IRC server(s):
- {BLCOEKD}ghxxxxx.info
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 uses the following credentials when accessing its IRC server:
- PASS Virus
- NICK VirUs-{random string 1}
- USER {random string 2} "" "{random string 3}" :{random string 2}
- JOIN #Weed# Virus
NOTES:
This worm sends a message to its server once successfully propagate through removable drives with the following format:
PRIVMSG #Weed.WSB# :0,1 ViroOo Own3d
0USB Driver 4 {Drive Letter}
It does not have rootkit capabilities.
It does not exploit any vulnerability.
SOLUTION
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
Step 4
Delete this registry value
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-33CF-AAX5-35GX1C642122}
- StubPath = "%System Root%\RESTORE\S-1-5-21-1482476501-1644491937-682003330-1013\Taquito.exe"
- StubPath = "%System Root%\RESTORE\S-1-5-21-1482476501-1644491937-682003330-1013\Taquito.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- Internet Security Services = "%System Root%\RESTORE\S-1-5-21-1482476501-1644491937-682003330-1013\Taquito.exe"
- Internet Security Services = "%System Root%\RESTORE\S-1-5-21-1482476501-1644491937-682003330-1013\Taquito.exe"
Step 5
Search and delete these folders
- %System Root%\RESTORE
- {Drive Letter}:\RESTORE
Step 6
Search and delete AUTORUN.INF files created by WORM_HAMWEQ.AIJ that contain these strings
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_HAMWEQ.AIJ. 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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