Analysis by: Christopher Daniel So

ALIASES:

TrojanDownloader:Win32/Tracur.Q (Microsoft), Trojan.Win32.Menti.gqyv (Kaspersky)

 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 downloads updated copies of itself from certain websites.

It redirects searches to a specific IP address if the search engine URL contains certain strings.

This Trojan may be dropped by other malware. It may be unknowingly downloaded by a user while visiting malicious websites.

  TECHNICAL DETAILS

File Size: Varies
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 26 Jun 2011
Payload: Downloads files

Arrival Details

This Trojan may be dropped by other malware.

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This Trojan drops the following copies of itself into the affected system:

  • %System%\{random file name}.exe
  • %System%\midimap32.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 files:

  • %System%\avmeter32.dll - detected by Trend Micro as TROJ_TRACUR.VY
  • %System%\shmedia32.dll - detected by Trend Micro as TROJ_TRACUR.VY
  • %System%\shmedia32.exe - detected by Trend Micro as TROJ_TRACUR.VY
  • %User Profile%\Application Data\SysWin\lsass.exe - detected by Trend Micro as TROJ_TRACUR.VY

(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.. %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 drops the following non-malicious files:

  • %System%\1652938413

(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 creates the following folders:

  • %User Profile%\Application Data\SysWin

(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.)

Autostart Technique

This Trojan registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random key}
DisplayName = "Performance Logs and Alerts"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random key}
ErrorControl = 0

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random key}
ImagePath = "%System%\{random file name}.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random key}
Start = 2

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random key}
Type = 10

It modifies the following registry entry(ies) to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Windows
AppInit_DLLs = "%System%\shmedia32.dll"

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

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\{05B1982F-0479-4E6F-9CA5-E8F41FAE4907}

HKEY_CLASSES_ROOT\CLSID\{05B1982F-0479-4E6F-9CA5-E8F41FAE4907}

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

HKEY_CLASSES_ROOT\CLSID\{05B1982F-0479-4E6F-9CA5-E8F41FAE4907}\
InprocServer32
(Default) = "%System%\avmeter32.dll"

It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random key}

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CLASSES_ROOT\.fsharproj

HKEY_CLASSES_ROOT\Cfbbbjkdkl

HKEY_CLASSES_ROOT\CLSID\{8efad686-2433-4cc7-9f23-929dfe22d792}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Tracing\FWCFG

It adds the following registry entries:

HKEY_CURRENT_USER\Identities
Curr version = "35"

HKEY_CURRENT_USER\Identities
Last Date = "{date of last execution}"

HKEY_CURRENT_USER\Identities
Send Inst = "ok"

HKEY_CURRENT_USER\Identities
Inst Date = "{date of installation}"

HKEY_CURRENT_USER\Identities
Popup count = "0"

HKEY_CURRENT_USER\Identities
Popup time = "0"

HKEY_CURRENT_USER\Identities
Popup date = "0"

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Tracing\FWCFG
EnableFileTracing = 0

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Tracing\FWCFG
EnableConsoleTracing = 0

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Tracing\FWCFG
FileTracingMask = ffff0000

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Tracing\FWCFG
ConsoleTracingMask = ffff0000

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Tracing\FWCFG
MaxFileSize = 100000

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Tracing\FWCFG
FileDirectory = "%windir%\tracing"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer
982bc1da = {random numbers}

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

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

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

Download Routine

This Trojan downloads updated copies of itself from the following websites:

  • http://{BLOCKED}.{BLOCKED}.153.48/{random string}
  • http://{BLOCKED}.{BLOCKED}.1.173/{random string}
  • http://{BLOCKED}.{BLOCKED}.1.174/{random string}

It saves the files it downloads using the following names:

  • %Windows%\{random file name}wow.exe - detected by Trend Micro as TROJ_TRACUR.VY

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

NOTES:

It creates the following registry entries to enable automatic execution of downloaded updated copy of itself at every system startup:

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

It redirects searches to the IP address {BLOCKED}.{BLOCKED}.117.107 if the search engine URL contains the following strings:

  • alltheweb.com
  • altavista.com
  • ask.com
  • bing.com
  • gigablast.com
  • google
  • hotbot.com
  • search.aol.com
  • search.lycos.com
  • search.netscape.com
  • search.yahoo.com
  • snap.com

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 8.250.03
FIRST VSAPI PATTERN DATE: 26 Jun 2011

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 delete files detected as TROJ_TRACUR.VY using either the Startup Disk or Recovery Console

[ Learn More ]

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
    • .fsharproj
  • In HKEY_CLASSES_ROOT
    • Cfbbbjkdkl
  • In HKEY_CLASSES_ROOT\CLSID
    • {05B1982F-0479-4E6F-9CA5-E8F41FAE4907}
  • In HKEY_CLASSES_ROOT\CLSID
    • {8efad686-2433-4cc7-9f23-929dfe22d792}
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • {random key}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects
    • {05B1982F-0479-4E6F-9CA5-E8F41FAE4907}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Tracing
    • FWCFG

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\Identities
    • Curr version="35"
  • In HKEY_CURRENT_USER\Identities
    • Last Date="{date of last execution}"
  • In HKEY_CURRENT_USER\Identities
    • Send Inst="ok"
  • In HKEY_CURRENT_USER\Identities
    • Inst Date="{date of installation}"
  • In HKEY_CURRENT_USER\Identities
    • Popup count="0"
  • In HKEY_CURRENT_USER\Identities
    • Popup time="0"
  • In HKEY_CURRENT_USER\Identities
    • Popup date="0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • XMLHTTP_UUID_Default={random numbers}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer
    • 982bc1da={random numbers}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {random file name}wow.exe="%Windows%\{random file name}wow.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %System%\{random file name}.exe="%System%\{random file name}.exe:*:Enabled:Windows Update Service"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\DomainProfile\AuthorizedApplications\List
    • %System%\{random file name}.exe="%System%\{random file name}.exe:*:Enabled:Windows Update Service"

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows
    • From: AppInit_DLLs="%System%\shmedia32.dll"
      To: AppInit_DLLs=""

Step 6

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. %System%\1652938413

Step 7

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. %User Profile%\Application Data\SysWin

Step 8

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