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TROJ_AGENTE.V

April 09, 2013
 ALIASES:

PWS:Win32/Yahoopass.H (Microsoft); Generic PUP.x!bp. (McAfee); Trojan Horse (Symantec); Trojan-Downloader.Tibs.gen (v) (Sunbelt); Trojan horse Generic14.AVQG (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.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

53,248 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

09 Apr 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.

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\{7F7C040E-6AEB-45ED-A6C9-3C1B8538CA3C}

Other System Modifications

This Trojan deletes the following files:

  • %System Root%\sys.bat

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{7F7C040E-6AEB-45ED-A6C9-3C1B8538CA3C}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{7F7C040E-6AEB-45ED-A6C9-3C1B8538CA3C}\InProcServer32

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
{random string} = "yes"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{7F7C040E-6AEB-45ED-A6C9-3C1B8538CA3C}\InProcServer32
ThreadingModel = "Apartment"

Dropping Routine

This Trojan drops the following files:

  • %System%\sys.dat
  • %System%\msonlinebb.dll

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

Other Details

This Trojan deletes itself after execution.

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer
    • Browser Helper Objects
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID
    • {7F7C040E-6AEB-45ED-A6C9-3C1B8538CA3C}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{7F7C040E-6AEB-45ED-A6C9-3C1B8538CA3C}
    • 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
    • {random string} = "yes"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{7F7C040E-6AEB-45ED-A6C9-3C1B8538CA3C}\InProcServer32
    • ThreadingModel = "Apartment"

Step 5

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%\sys.dat
  • %System%\msonlinebb.dll

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_AGENTE.V. 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 7

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %System Root%\sys.bat


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