TROJ_TRACUR.AC

 Analysis by: Cris Nowell Pantanilla

 ALIASES:

Trojan.Win32.Vapsup.adqs (Kaspersky), TrojanDownloader:Win32/Tracur.P (Microsoft)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This Trojan searches for .DLL files in the System folder. It uses {DLL name}wow.exe as the malware file name. It executes a certain command to bypass Windows Firewall.

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

24 Jun 2009

Payload:

Bypasses Windows Firewall

Arrival Details

This Trojan 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 Trojan drops the following non-malicious files:

  • %System%\{Random Hex}\lock
  • %System%\{Random Hex}\unrar.exe

(Note: %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.)

It drops the following copies of itself into the affected system:

  • %Windows%\{random}wow.exe

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

It creates the following folders:

  • %System%\{Random Hex}
  • %System%\{Random Hex}\b
  • %System%\{Random Hex}\h

(Note: %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.)

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{random}wow.exe = "%Windows%\{random}wow.exe"

Other System Modifications

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\AuthorizedApplications\
List
%Windows%\{random}wow.exe = "%Windows%\{random}wow.exe:*:Enabled:Windows Update Service"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%Windows%\{random}wow.exe = "%Windows%\{random}wow.exe:*:Enabled:Windows Update Service"

Download Routine

This Trojan connects to the following website(s) to download and execute a malicious file:

  • http://{BLOCKED}9.{BLOCKED}5.49.220/update/
  • http://{BLOCKED}.{BLOCKED}8.240.82/update/
  • http://{BLOCKED}.{BLOCKED}7.53.210/update/
  • http://{BLOCKED}.{BLOCKED}7.153.48/update/

It saves the files it downloads using the following names:

  • %System%\{Random Hex}\update.exe

(Note: %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.)

As of this writing, the said sites are inaccessible.

NOTES:

It searches for .DLL files in the System folder. It uses {DLL name}wow.exe as the malware file name

It executes the following command to bypass Windows Firewall:

%System%\netsh firewall add allowedprogram
program="%Windows%\{random}wow.exe"name="Windows Update Service"
mode=ENABLE scope=ALL profile=ALL

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

6.218.01

FIRST VSAPI PATTERN DATE:

24 Jun 2009

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

Identify and terminate files detected as TROJ_TRACUR.AC

[ Learn More ]
  1. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  2. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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\CurrentVersion\Run
    • {random}wow.exe = "%Windows%\{random}wow.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\DomainProfile\AuthorizedApplications\List
    • %Windows%\{random}wow.exe = "%Windows%\{random}wow.exe:*:Enabled:Windows Update Service"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %Windows%\{random}wow.exe = "%Windows%\{random}wow.exe:*:Enabled:Windows Update Service"

Step 4

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.
  • %System%\{Random Hex}\

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_TRACUR.AC. 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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