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Threat Encyclopedia

TROJ_TRACUR.SMB

ANALYSIS BY

Christopher Daniel So


ALIASES:

TrojanDownloader.Win32.Tracur.a (Sunbelt)

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 may be downloaded by other malware/grayware from remote sites. It 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:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

26 Apr 2011

Payload:

Downloads files

Arrival Details

This Trojan may be downloaded by the following malware/grayware from remote sites:

  • TROJ_TRACUR.SMA

It 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
  • %System%\shmedia32.exe
  • %User Profile%\Application Data\SysWin\lsass.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It drops the following non-malicious files:

  • %System%\unrar.exe

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

It creates the following folders:

  • %User Profile%\Application Data\SysWin

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It terminates the execution of the copy it initially executed and executes the copy it drops instead.

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\HidServ32
Type = 10

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\HidServ32
Start = 2

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\HidServ32
ErrorControl = 0

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\HidServ32
ImagePath = "%System%\{random file name}.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\HidServ32
DisplayName = "Human Interface Device Access "

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\HidServ32
ObjectName = "LocalSystem"

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\HidServ32

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CLASSES_ROOT\.fsharproj

HKEY_CLASSES_ROOT\Cfbbbjkdkl

It adds the following registry entries:

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

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

HKEY_CURRENT_USER\Identities
Curr version = "35"

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

HKEY_CURRENT_USER\Identities
Send Inst = "ok"

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

HKEY_CURRENT_USER\Identities
Popup count = "0"

HKEY_CURRENT_USER\Identities
Popup time = "0"

HKEY_CURRENT_USER\Identities
Popup date = "0"

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

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"

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"

Download Routine

This Trojan connects to the following URL(s) to download its configuration file:

  • http://{BLOCKED}.1.173/doit/{random characters}
  • http://{BLOCKED}.1.174/tornado/{random characters}

It saves the files it downloads using the following names:

  • %System%\{random folder}\frt{random number}.rar

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

NOTES:
The downloaded configuration file contains the URLs containing the update. The URLs are saved in the file %System%\1652938413. However, the configuration file is not saved in the computer. It downloads updates of itself from the URLs in the configuration file. The downloaded update is a compressed RAR archive. It uses the dropped file %System%\unrar.exe to extract the compressed updated copy of the malware. Trend Micro detects the downloaded update as either TROJ_TRACUR.SMA or TROJ_TRACUR.SMB.

SOLUTION

Minimum Scan Engine:

8.900

VSAPI OPR PATTERN File:

8.123.00

VSAPI OPR PATTERN Date:

27 Apr 2011

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 TROJ_TRACUR.SMB

    TROJ_TRACUR.SMA
    TROJ_TRACUR.SMB

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • HidServ32
  • In HKEY_CLASSES_ROOT
    • .fsharproj
  • In HKEY_CLASSES_ROOT
    • Cfbbbjkdkl

Step 5

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_CURRENT_USER\Identities
    • Curr version=35
  • In HKEY_CURRENT_USER\Identities
    • Last Date={last date of execution}
  • In HKEY_CURRENT_USER\Identities
    • Send Inst=ok
  • In HKEY_CURRENT_USER\Identities
    • Inst Date={installation date}
  • 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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer
    • 982bc1da={random values}
  • 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
  • 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

Step 6

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 7

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%\unrar.exe
%System%\{random folder}\frt{random number}.rar

Step 8

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