WORM_NUSUMP.B
Symantec: W32.SillyIRC; Microsoft: Worm:Win32/Nusump; Kaspersky: Trojan.Win32.VBKrypt.jgg
Windows 2000, Windows XP, Windows Server 2003

Threat Type: Worm
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
This worm arrives via removable drives. It may be dropped by other malware. It may be unknowingly downloaded by a user while visiting malicious websites.
It adds registry entries to enable its automatic execution at every system startup.
It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.
It connects to a website to send and receive information.
TECHNICAL DETAILS
86,016 bytes
PE
Yes
10 Dec 2010
Arrival Details
This worm arrives via removable drives.
It may be dropped by other malware.
It may be unknowingly downloaded by a user while visiting malicious websites.
Installation
This worm drops the following copies of itself into the affected system:
- %User Temp%\{random name}.exe
(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)
Autostart Technique
This worm adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Windows = %User Temp%\{random name}.exe
HKEY_LOCAL_MACHINE\Software\Microsoft\
Active Setup\Installed Components\{36A5A0DB-297E-FDE2-0501-060104070800}
StubPath = %User Temp%\{random name}.exe
Propagation
This worm creates the following folders in all removable drives:
- {random name}
It drops the following copy(ies) of itself in all removable drives:
- {random name}\{random name}.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]
;{garbage}
Open = .\{random folder name}\{random file name}.exe
;{garbage}
shell\open\Command = {random folder name}\{random file name}.exe
;{garbage}
shell\explore\Command = {random folder name}\{random file name}.exe
;{garbage}
UseAutoPlay=1
Backdoor Routine
This worm connects to the following websites to send and receive information:
- http://{BLOCKED}s-call.com/index.php?{parameters}
SOLUTION
8.900
under testing
Step 1
For Windows ME and XP users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.
Step 2
Scan your computer with your Trend Micro product and note files detected as WORM_NUSUMP.B
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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- Windows = %User Temp%\{random name}.exe
- Windows = %User Temp%\{random name}.exe
Step 5
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\Software\Microsoft\Active Setup\Installed Components
- {36A5A0DB-297E-FDE2-0501-060104070800}
- {36A5A0DB-297E-FDE2-0501-060104070800}
Step 6
Search and delete AUTORUN.INF files created by WORM_NUSUMP.B that contain these strings
Step 7
Search and delete this folder
- {removable drive}:\{random name}
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_NUSUMP.B 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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