WORM_UPDATER.AC
Worm:Win32/Networm.A (Microsoft), W32/Updater.I@mm (Fortinet), Email-Worm.Win32.Atak (Ikarus), Win32/Pepex.I worm (ESET)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Worm
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This worm arrives as an attachment to email messages spammed by other malware/grayware or malicious users.
It propagates via shared networks and drops copies of itself into available networks.
TECHNICAL DETAILS
42,496 bytes
EXE
Yes
26 Dec 2013
Arrival Details
This worm arrives as an attachment to email messages spammed by other malware/grayware or malicious users.
It may arrive via network shares.
Installation
This worm drops the following copies of itself into the affected system and executes them:
- C:\WINNT\Isass.exe
- C:\WINDOWS\Isass.exe
It drops the following files:
- %Windows%\stm8.inf
(Note: %Windows% is the Windows folder, which is usually C:\Windows.)
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\wgautr
Type = "10"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wgautr
Start = "3"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wgautr
ErrorControl = "1"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wgautr
ImagePath = "C:\WINDOWS\Isass.exe" or "C:\WINNT\Isass.exe"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wgautr
DisplayName = "Windows Genuine Updater"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wgautr
ObjectName = "LocalSystem"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wgautr\Security
Security = "{hex values}"
It adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Local Security Authority Process = "{malware path and file name} %1"
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\wgautr
Propagation
This worm propagates via shared networks and drops copies of itself into available networks.
Other Details
This worm connects to the following possibly malicious URL:
- {BLOCKED}.{BLOCKED}.65.27
- {BLOCKED}.{BLOCKED}.67.26
- {BLOCKED}.{BLOCKED}.73.27
- {BLOCKED}.{BLOCKED}.68.27
- {BLOCKED}.{BLOCKED}.133.26
- {randomly generated IP address}
SOLUTION
9.700
10.498.04
26 Dec 2013
10.499.00
27 Dec 2013
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
Restart in Safe Mode
Step 3
Delete this registry key
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
- wgautr
- wgautr
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\Windows\CurrentVersion\Run
- Local Security Authority Process = "{malware path and file name} %1"
- Local Security Authority Process = "{malware path and file name} %1"
Step 5
Search and delete this file
- %Windows%\stm8.inf
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_UPDATER.AC. 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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