WORM_OTORUN.EF
Backdoor:Win32/Ursap!rts (Microsoft); Trojan.Win32.Buzus.epzc (Kaspersky)
Windows 2000, Windows XP, Windows Server 2003
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Worm
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This worm arrives by connecting affected removable drives to a system.
It drops copies of itself into all the removable drives connected to an affected system. 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
Arrival Details
This worm arrives by connecting affected removable drives to a system.
Installation
This worm drops the following copies of itself into the affected system:
- %User Profile%\Application Data\wlmop.exe
(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)
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 = "%User Profile%\Application Data\wlmop.exe"
Propagation
This worm creates the following folders in all removable drives:
- sond
It drops copies of itself into all the removable drives connected to an affected system.
It drops the following copy(ies) of itself in all removable drives:
- sond\Mircr0dll.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:
;{random characters}
[AutoRun
;{random characters}
open=sond/Mircr0dll.exe
;{random characters}
:call
;{random characters}
icon=%SystemRoot%\system32\SHELL32.dll,4
;{random characters}
:cmp
;{random characters}
action=Open folder to view files using Windows Explorer
;{random characters}
shell\\open\\command=sond/Mircr0dll.exe
;{random characters}
:jmp5
;{random characters}
shell\\explore\command=sond/Mircr0dll.exe
;{random characters}
useautoplay=1
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
Identify and delete files detected as WORM_OTORUN.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 = "%User Profile%\Application Data\wlmop.exe"
- Taskman = "%User Profile%\Application Data\wlmop.exe"
Step 4
Search and delete this folder
- {removable drive letter}:\sond
Step 5
Search and delete AUTORUN.INF files created by WORM_OTORUN.EF that contain these strings
;{random characters}
[AutoRun
;{random characters}
open=sond/Mircr0dll.exe
;{random characters}
:call
;{random characters}
icon=%SystemRoot%\system32\SHELL32.dll,4
;{random characters}
:cmp
;{random characters}
action=Open folder to view files using Windows Explorer
;{random characters}
shell\open\command=sond/Mircr0dll.exe
;{random characters}
:jmp5
;{random characters}
shell\explore\command=sond/Mircr0dll.exe
;{random characters}
useautoplay=1
Step 6
Scan your computer with your Trend Micro product to delete files detected as WORM_OTORUN.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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