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WORM_AUTORUN.GYT

November 29, 2011
 Analysis by: Christopher Daniel So
 ALIASES:

Worm:Win32/Cridex.B (Microsoft), W32.SillyDC (Symantec), , PWS-Zbot.gen.ni (McAfee), Worm.Win32.AutoRun.czje (Kaspersky)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • 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 adds registry entries to enable its automatic execution at every system startup.

It deletes registry entries, causing some applications and programs to not function properly.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

58,368 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

21 Nov 2011

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:

  • %User Profile%\Application Data\KB00445963.EXE

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

It terminates the execution of the copy it initially executed and executes the copy it drops instead.

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
KB00445963.exe = "%User Profile%\Application Data\KB00445963.EXE"

Other System Modifications

This worm adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
GlobalUserOffline = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyEnable = "0"

It deletes the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
AutoConfigURL = "{user defined}"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyOverride = "{user defined}"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
ProxyServer = "{user defined}"

Other Details

This worm connects to the following possibly malicious URL:

  • http://{BLOCKED}zerberze.ru/724/in/

It deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine:

9.200

VSAPI OPR PATTERN File:

8.591.00

VSAPI OPR PATTERN Date:

22 Nov 2011

Step 1

Prior to scanning your system, Windows XP, Windows Server 2003, Windows Vista, and Windows 7 users should make sure you disable System Restore to be able to conduct a full scan.

Step 2

Restart in Safe Mode

[ Learn More ]

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • GlobalUserOffline = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • ProxyEnable = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • KB00445963.exe = "%User Profile%\Application Data\KB00445963.EXE"

Step 4

Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_AUTORUN.GYT 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.

Step 5

Restore these deleted registry keys/values from backup

*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
AutoConfigURL = "{user defined}"



HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
ProxyOverride = "{user defined}"



HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
ProxyServer = "{user defined}"


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