ALIASES:

Trojan:Win32/Tracur.P (Microsoft); Downloader-BMN.gen.ak (McAfee); Trojan.Gen (Symantec); Trojan.Win32.Direr.cm (Kaspersky); TrojanDownloader.Win32.Tracur.a (v) (Sunbelt); Trojan horse Cryptic.BML (AVG)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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.

  TECHNICAL DETAILS

File Size: 1,099,264 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 21 Jul 2013

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 copies of itself into the affected system:

  • %System%\usrsvpia32.exe

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

Autostart Technique

This Trojan 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\{0EB5810F-BE78-4173-8DC1-B02190EEA625}

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{6A2B3E08-BF8B-5FCB-682F-A68AF7967843}

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CLASSES_ROOT\Htbwcznlug\CLSID

HKEY_CLASSES_ROOT\CLSID\{8944c067-e372-498d-960b-fa25b53f8d29}

HKEY_USERS\.DEFAULT\Software\
Htbwcznlug\CLSID

HKEY_USERS\S-1-5-19\Software\
Htbwcznlug\CLSID

HKEY_USERS\S-1-5-19_Classes\Software\
Htbwcznlug\CLSID

HKEY_USERS\S-1-5-20\Software\
Htbwcznlug\CLSID

HKEY_USERS\S-1-5-20_Classes\Software\
Htbwcznlug\CLSID

HKEY_USERS\S-1-5-21-1645522239-1292428093-682003330-1003\Software\
Htbwcznlug\CLSID

HKEY_USERS\S-1-5-21-1645522239-1292428093-682003330-1003_Classes\Software\
Htbwcznlug\CLSID

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.fsharproj\PersistentHandler

HKEY_CLASSES_ROOT\CLSID\{0EB5810F-BE78-4173-8DC1-B02190EEA625}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{0EB5810F-BE78-4173-8DC1-B02190EEA625}\InprocServer32

HKEY_CLASSES_ROOT\CLSID\{6A2B3E08-BF8B-5FCB-682F-A68AF7967843}

HKEY_CLASSES_ROOT\CLSID\{6A2B3E08-BF8B-5FCB-682F-A68AF7967843}\
InProcServer32

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
XMLHTTP_UUID_Default = "{random values}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{0EB5810F-BE78-4173-8DC1-B02190EEA625}\InprocServer32
ThreadingModel = "Both"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\AuthorizedApplications\
List
%System%\usrsvpia32.exe = "%System%\usrsvpia32.exe:*:Enabled:Windows Update Service"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%System%\usrsvpia32.exe = "%System%\usrsvpia32.exe:*:Enabled:Windows Update Service"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer
68ad0fd0 = "{random values}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Windows
LoadAppInit_DLLs = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{6A2B3E08-BF8B-5FCB-682F-A68AF7967843}\InProcServer32
ThreadingModel = "Apartment"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{6A2B3E08-BF8B-5FCB-682F-A68AF7967843}
NoExplorer = "1"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Windows
AppInit_Dlls = "%System%\safrdm32.dll"

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\{B6FB50C5-70BB-4b1e-97E7-64B307776E8A}

Dropping Routine

This Trojan drops the following files:

  • %System%\avifile32.dll
  • %System%\safrdm32.dll
  • %System%\02000000ee0dd8001091P.manifest
  • %System%\02000000ee0dd8001091C.manifest
  • %System%\02000000ee0dd8001091O.manifest
  • %System%\02000000ee0dd8001091S.manifest
  • %System%\jgmd40032.exe

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

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}.53.210/{random path}

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.300

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

Close all opened browser windows

Step 3

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_CLASSES_ROOT\Htbwcznlug
    • CLSID
  • In HKEY_CLASSES_ROOT\CLSID
    • {8944c067-e372-498d-960b-fa25b53f8d29}
  • In HKEY_USERS\.DEFAULT\Software\Htbwcznlug
    • CLSID
  • In HKEY_USERS\S-1-5-19\Software\Htbwcznlug
    • CLSID
  • In HKEY_USERS\S-1-5-19_Classes\Software\Htbwcznlug
    • CLSID
  • In HKEY_USERS\S-1-5-20\Software\Htbwcznlug
    • CLSID
  • In HKEY_USERS\S-1-5-20_Classes\Software\Htbwcznlug
    • CLSID
  • In HKEY_USERS\S-1-5-21-1645522239-1292428093-682003330-1003\Software\Htbwcznlug
    • CLSID
  • In HKEY_USERS\S-1-5-21-1645522239-1292428093-682003330-1003_Classes\Software\Htbwcznlug
    • CLSID
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.fsharproj
    • PersistentHandler
  • In HKEY_CLASSES_ROOT\CLSID
    • {0EB5810F-BE78-4173-8DC1-B02190EEA625}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{0EB5810F-BE78-4173-8DC1-B02190EEA625}
    • InprocServer32
  • In HKEY_CLASSES_ROOT\CLSID
    • {6A2B3E08-BF8B-5FCB-682F-A68AF7967843}
  • In HKEY_CLASSES_ROOT\CLSID\{6A2B3E08-BF8B-5FCB-682F-A68AF7967843}
    • InProcServer32

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\Internet Explorer\Main
    • XMLHTTP_UUID_Default = "{random values}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{0EB5810F-BE78-4173-8DC1-B02190EEA625}\InprocServer32
    • ThreadingModel = "Both"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\DomainProfile\AuthorizedApplications\List
    • %System%\usrsvpia32.exe = "%System%\usrsvpia32.exe:*:Enabled:Windows Update Service"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %System%\usrsvpia32.exe = "%System%\usrsvpia32.exe:*:Enabled:Windows Update Service"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer
    • 68ad0fd0 = "{random values}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows
    • LoadAppInit_DLLs = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{6A2B3E08-BF8B-5FCB-682F-A68AF7967843}\InProcServer32
    • ThreadingModel = "Apartment"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects\{6A2B3E08-BF8B-5FCB-682F-A68AF7967843}
    • NoExplorer = "1"

Step 5

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows
    • AppInit_Dlls = "%System%\safrdm32.dll"

Step 6

Search and delete these components

[ Learn More ]
There may be some components 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%\avifile32.dll
  • %System%\safrdm32.dll
  • %System%\02000000ee0dd8001091P.manifest
  • %System%\02000000ee0dd8001091C.manifest
  • %System%\02000000ee0dd8001091O.manifest
  • %System%\02000000ee0dd8001091S.manifest
  • %System%\jgmd40032.exe

Step 7

Scan your computer with your Trend Micro product to delete files detected as TROJ_TRACUR.AW. 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 8

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.

  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion
    • {B6FB50C5-70BB-4b1e-97E7-64B307776E8A}


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