WORM_NECAST.J
Trojan horse Dropper.Generic7.ASBX (AVG), Worm:MSIL/Necast.J (Microsoft)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
Threat Type: Worm
Destructiveness: No
Encrypted:
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 executes the files it drops, prompting the affected system to exhibit the malicious routines they contain.
TECHNICAL DETAILS
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 and executes the following files:
- %User Temp%\rundall32.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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)
Other System Modifications
This worm adds the following registry keys:
HKEY_CURRENT_USER\Software\86c7df5d8ecbddfca22776d30d564e74
It adds the following registry entries:
HKEY_CURRENT_USER\Environment
SEE_MASK_NOZONECHECKS = "1"
HKEY_CURRENT_USER\Software\86c7df5d8ecbddfca22776d30d564e74
US = "@"
Dropping Routine
This worm executes the files it drops, prompting the affected system to exhibit the malicious routines they contain.
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
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_CURRENT_USER\Software
- 86c7df5d8ecbddfca22776d30d564e74
- 86c7df5d8ecbddfca22776d30d564e74
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_CURRENT_USER\Environment
- SEE_MASK_NOZONECHECKS = "1"
- SEE_MASK_NOZONECHECKS = "1"
- In HKEY_CURRENT_USER\Software\86c7df5d8ecbddfca22776d30d564e74
- US = "@"
- US = "@"
Step 4
Search and delete these files
- %User Temp%\rundall32.exe
Step 5
Scan your computer with your Trend Micro product to delete files detected as
*Note: 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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