ALIASES:

TrojanSpy:Win32/Ranbyus.B (Microsoft)

 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 disables Task Manager, Registry Editor, and Folder Options.

  TECHNICAL DETAILS

File Size: 138,752 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 05 Nov 2011

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%\dllhosl.exe

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

Other System Modifications

This Trojan deletes the following files:

  • %User Profile%\Cookies\index.dat

(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 adds the following registry keys:

HKEY_USERS\S-1-5-21-4025279379-4087772427-2915903831-500\Software\
Microsoft\Windows\CurrentVersion\
policies\Explorer\Run

HKEY_USERS\S-1-5-21-4025279379-4087772427-2915903831-500\Software\
BIFIT

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
System Information = {random values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%System%\svchost.exe = "%System%\svchost.exe:*:Enabled:System Rescue"

It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run
System Rescue = "%System%\dllhosl.exe"

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows NT\CurrentVersion\SystemRestore

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}5.in/tribuna/index.php?{random characters}
  • http://{BLOCKED}5.in/tribuna/index.php?{random characters}

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.200

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

Enable Registry Editor, Task Manager, and Folder options

[ Learn More ]
By doing this step, you also enable other applications/programs disabled by this malware/grayware/spyware.

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_USERS\S-1-5-21-4025279379-4087772427-2915903831-500\Software\Microsoft\Windows\CurrentVersion\policies\Explorer
    • Run
  • In HKEY_USERS\S-1-5-21-4025279379-4087772427-2915903831-500\Software
    • BIFIT

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\Windows NT\CurrentVersion\Winlogon
    • System Information={random values}
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %System%\svchost.exe="%System%\svchost.exe:*:Enabled:System Rescue"

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_KRAP.SML. 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 6

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. %User Profile%\Cookies\index.dat

Step 7

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 NT\CurrentVersion
    • SystemRestore


Did this description help? Tell us how we did.