WORM_AMBLER.SMZ

 Modified by: Sabrina Lei Sioting

 ALIASES:

Worm:Win32/Ambler.A (Microsoft), Mal/Ambler-B (Sophos), W32/Ambler.BM!tr (Fortinet), Worm.Win32.Ambler (Ikarus), TrojanSpy.Amber.uj (VBA32),

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Propagates via removable drives


This worm arrives by connecting affected removable drives to a system. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It disables Task Manager, Registry Editor, and Folder Options.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

It steals certain information from the system and/or the user. It logs a user's keystrokes to steal information. It sends the information it gathers to remote sites.

  TECHNICAL DETAILS

File Size:

49,664 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

19 Jul 2010

Payload:

Steals information, Drops files

Arrival Details

This worm arrives by connecting affected removable drives to a system.

It 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 non-malicious files:

  • %System%\iafzb
  • %System%\klgd.bmp
  • %System%\bdf.txt
  • %System%\ccdf.txt
  • %System%\eeef.txt
  • %System%\fsc.txt
  • %System%\ide.txt
  • %System%\lbbf.txt
  • %System%\lrg.txt
  • %System%\xef.txt

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • jhhiuerf_vktyfd
  • mbv
  • jhhiuerf

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\RunOnce
hihg = "rundll32.exe vktyfd.dll,ID"

It registers itself as a BHO to ensure its automatic execution every time Internet Explorer is used by adding the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{94EA03C3-5988-4428-A5BF-5AB34C82C806}

Other System Modifications

This worm adds the following registry entries as part of its installation routine:

HKEY_CLASSES_ROOT\CLSID\{94EA03C3-5988-4428-A5BF-5AB34C82C806}
{default} = "Internet Explorer Plugin"

HKEY_CLASSES_ROOT\CLSID\{94EA03C3-5988-4428-A5BF-5AB34C82C806}\
InprocServer32
{default} = "vktyfd.dll"

HKEY_LOCAL_MACHINE\SOFTWARE\Rapport
JGG = "{random characters}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{94EA03C3-5988-4428-A5BF-5AB34C82C806}
{default} = "Internet Explorer Plugin"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{94EA03C3-5988-4428-A5BF-5AB34C82C806}\InprocServer32
{default} = "vktyfd.dll"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{E3428D3F-3725-4FE1-986A-57EAE3E08123}
{default} = "IE development helper "

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{E3428D3F-3725-4FE1-986A-57EAE3E08123}
StubPath = "rundll32 vktyfd.dll,laspi"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Enable Browser Extensions = "yes"

It adds the following registry keys as part of its installation routine:

HKEY_CLASSES_ROOT\CLSID\{94EA03C3-5988-4428-A5BF-5AB34C82C806}

HKEY_LOCAL_MACHINE\SOFTWARE\Rapport

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{94EA03C3-5988-4428-A5BF-5AB34C82C806}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{E3428D3F-3725-4FE1-986A-57EAE3E08123}

It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableRegistryTools = "1"

Propagation

This worm creates the following folders in all removable drives:

  • RECYCLER

It drops the following copy(ies) of itself in all removable drives:

  • RECYCLER\recycld.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]
open=RECYCLER\recycld.exe e
icon=%SystemRoot%\system32\SHELL32.dll,4
action=Open folder to view files
shell\open=Open
shell\open\command=RECYCLER\recycld.exe
shell\open\default=1

Dropping Routine

This worm drops the following files:

  • %System%\vktyfd.dll - detected as TROJ_AMBLER.SG

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

Information Theft

This worm steals the following information:

  • MSN Explorer signup credentials
  • IE password-protected sites
  • IE auto-complete fields
  • Auto-complete passwords
  • Protected storage
  • Outlook Express
  • Cookies

It logs a user's keystrokes to steal information.

It sends the information it gathers to remote sites.

Stolen Information

This worm saves the stolen information in the following file:

  • %System%\bdf.txt
  • %System%\ccdf.txt
  • %System%\eeef.txt
  • %System%\fsc.txt
  • %System%\ide.txt
  • %System%\lbbf.txt
  • %System%\lrg.txt
  • %System%\xef.txt

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

NOTES:

The dropped AUTORUN.INF is detected as MAL_OTORUND.

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

7.320.10

FIRST VSAPI PATTERN DATE:

19 Jul 2010

VSAPI OPR PATTERN File:

7.321.00

VSAPI OPR PATTERN Date:

20 Jul 2010

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

Remove the malware/grayware file dropped/downloaded by WORM_AMBLER.SMZ

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

To enable Registry Editor, Task Manager, and Folder options:

  1. Open Notepad. To do this:
    • For Windows 2000, XP, and Server 2003 users:
      Click Start > Run, type Notepad in the text box provided, then press Enter.
    • For Windows Vista and 7 users:
      Click Start > type NotepadOn Error Resume Next Set shl = WScript.CreateObject("WScript.Shell") shl.RegWrite "HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\DisableTaskMgr", "0", "REG_DWORD" shl.RegWrite "HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\DisableRegistryTools", "0", "REG_DWORD" , then press Enter.
  2. Copy and paste the following script:
  3. Save this file asOn Error Resume Next Set shl = WScript.CreateObject("WScript.Shell") shl.RegWrite "HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\DisableTaskMgr", "0", "REG_DWORD" shl.RegWrite "HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\DisableRegistryTools", "0", "REG_DWORD" On Error Resume Next Set shl = WScript.CreateObject("WScript.Shell") shl.RegWrite "HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\DisableTaskMgr", "0", "REG_DWORD" shl.RegWrite "HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\DisableRegistryTools", "0", "REG_DWORD" C:RESTORE.VBS.
  4. Click Start>Run again, type C:RESTORE.VBS in the text box provided, then press Enter.
  5. Click Yes at theOn Error Resume Next Set shl = WScript.CreateObject("WScript.Shell") shl.RegWrite "HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\DisableTaskMgr", "0", "REG_DWORD" shl.RegWrite "HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\DisableRegistryTools", "0", "REG_DWORD" On Error Resume Next Set shl = WScript.CreateObject("WScript.Shell") shl.RegWrite "HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\DisableTaskMgr", "0", "REG_DWORD" shl.RegWrite "HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\System\\DisableRegistryTools", "0", "REG_DWORD" prompt of the message box to execute the .VBS file.

Step 5

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_CLASSES_ROOT\CLSID
    • {94EA03C3-5988-4428-A5BF-5AB34C82C806}
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • Rapport
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID
    • {94EA03C3-5988-4428-A5BF-5AB34C82C806}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components
    • {E3428D3F-3725-4FE1-986A-57EAE3E08123}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects
    • {94EA03C3-5988-4428-A5BF-5AB34C82C806}

Step 6

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\Internet Explorer\Main
    • Enable Browser Extensions = "yes"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\RunOnce
    • hihg = "rundll32.exe vktyfd.dll,ID"

Step 7

Search and delete these folders

[ 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. {drive letter}\RECYCLER

Step 8

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.  
  • %System%\iafzb
  • %System%\klgd.bmp
  • %System%\bdf.txt
  • %System%\ccdf.txt
  • %System%\eeef.txt
  • %System%\fsc.txt
  • %System%\ide.txt
  • %System%\lbbf.txt
  • %System%\lrg.txt
  • %System%\xef.txt

Step 9

Search and delete AUTORUN.INF files created by WORM_AMBLER.SMZ that contain these strings

[ Learn More ]
[autorun] 
open=RECYCLER\recycld.exe e
icon=%SystemRoot%\system32\SHELL32.dll,4 
action=Open folder to view files 
shell\open=Open 
shell\open\command=RECYCLER\recycld.exe 
shell\open\default=1

Step 10

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