WORM_HAMWEQ.EF
Worm:Win32/Hamweq.A (Microsoft); Backdoor.Trojan (Symantec); W32/Rimecud (McAfee); W32/Hamweq-N (Sophos)
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Worm
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
This worm 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.
TECHNICAL DETAILS
45,056 bytes
EXE
Yes
21 Oct 2011
Arrival Details
This worm 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 files:
- %System Root%\RECYCLER\R-1-5-21-1482476501-1644491937-682003330-1013\Desktop.ini
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
It drops the following copies of itself into the affected system:
- %System Root%\RECYCLER\R-1-5-21-1482476501-1644491937-682003330-1013\acleaner.exe
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
It creates the following folders:
- %System Root%\RECYCLER\R-1-5-21-1482476501-1644491937-682003330-1013
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
Autostart Technique
This worm adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Taskman = "%System Root%\RECYCLER\R-1-5-21-1482476501-1644491937-682003330-1013\acleaner.exe"
Propagation
This worm creates the following folders in all removable drives:
- RECYCLER
It drops the following copy(ies) of itself in all removable drives:
- {Removable Drive}:\RECYCLER\R-1-5-21-1482476501-1644491937-682003330-1013\acleaner.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:
{garbage characters}
[autorun]
open=RECYCLER\R-1-5-21-1482476501-1644491937-682003330-1013\acleaner.exe
{garbage characters}
icon=%SystemRoot%\system32\SHELL32.dll,4
action=Open folder to view files
shell\open=Open
shell\open\command=RECYCLER\R-1-5-21-1482476501-1644491937-682003330-1013\acleaner.exe
{garbage characters}
shell\open\default=1
{garbage characters}
Other Details
This worm connects to the following possibly malicious URL:
- dl.{BLOCKED}k.com
SOLUTION
9.200
8.838.04
15 Mar 2012
8.839.00
15 Mar 2012
Step 1
For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.
Step 2
Identify and delete files detected as WORM_HAMWEQ.EF using either the Startup Disk or Recovery Console
Step 3
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\Windows NT\CurrentVersion\Winlogon
- Taskman = "%System Root%\RECYCLER\R-1-5-21-1482476501-1644491937-682003330-1013\acleaner.exe"
- Taskman = "%System Root%\RECYCLER\R-1-5-21-1482476501-1644491937-682003330-1013\acleaner.exe"
Step 4
Search and delete these folders
- %System Root%\RECYCLER\R-1-5-21-1482476501-1644491937-682003330-1013
- {Removable Drive}:\RECYCLER
Step 5
Search and delete AUTORUN.INF files created by WORM_HAMWEQ.EF that contain these strings
[autorun]
open=RECYCLER\R-1-5-21-1482476501-1644491937-682003330-1013\acleaner.exe
{garbage characters}
icon=%SystemRoot%\system32\SHELL32.dll,4
action=Open folder to view files
shell\open=Open
shell\open\command=RECYCLER\R-1-5-21-1482476501-1644491937-682003330-1013\acleaner.exe
{garbage characters}
shell\open\default=1
{garbage characters}
Step 6
Scan your computer with your Trend Micro product to delete files detected as WORM_HAMWEQ.EF. 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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