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WORM_AUTORUN.PB
Aliases: TrojanDropper:Win32/Emold.C (Microsoft); Downloader-AAP (McAfee); W32.SillyFDC (Symantec); Worm.Win32.Downloader.wh (Kaspersky); Worm.Win32.Emold (v) (Sunbelt)
Malware type: Worm
Destructive: No
Platform: Windows 2000, Windows XP, Windows Server 2003
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.

Technical Details


File size: 33,792 bytes
File type: EXE
Memory resident: No
Initial samples received date: 20 Oct 2012

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 copies of itself into the affected system:

  • %Program Files%\Microsoft Common\svchost.exe

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files.)

It creates the following folders:

  • %Program Files%\Microsoft Common

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files.)

Other System Modifications

This worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
explorer.exe

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
explorer.exe
Debugger = "%Program Files%\Microsoft Common\svchost.exe"

Dropping Routine

This worm drops the following files:

  • %User Temp%\rdl1.tmp
  • %User Temp%\rdl2.tmp
  • %System%\DRIVERS\asyncmac.sys
  • A:\system.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.. %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Other Details

This worm connects to the following possibly malicious URL:

  • http://{BLOCKED}xt.cn/ld.php?{random characters}
  • http://{BLOCKED}iw123.com/ld.php?v=1&rs=1756172240&n=1&uid=1

This report is generated via an automated analysis system.

Solution


Minimum scan engine: 9.300

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

Delete this registry key

[ Learn more ]

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\Image File Execution Options
    • explorer.exe

Step 3

Delete this registry value

[ Learn more ]

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\Image File Execution Options\explorer.exe
    • Debugger = "%Program Files%\Microsoft Common\svchost.exe"

Step 4

Search and delete these files

[ Learn more ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %User Temp%\rdl1.tmp
  • %User Temp%\rdl2.tmp
  • %System%\DRIVERS\asyncmac.sys
  • A:\system.exe

Step 5

Search and delete this folder

[ Learn more ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %Program Files%\Microsoft Common

Step 6

Scan your computer with your Trend Micro product to delete files detected as WORM_AUTORUN.PB. 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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Analysis By: Automation

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