Analysis by: Christopher Daniel So
ALIASES:

Trojan:Win32/Boaxxe.E (Microsoft), Trojan.Win32.Rudlin.as (Kaspersky)

 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 may be dropped by other malware.

  TECHNICAL DETAILS

File Size: 187,944 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 06 Apr 2012

Arrival Details

This Trojan may be dropped by other malware.

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\ldinihyu
ImagePath = "%SystemRoot%\System32\svchost.exe -k netsvcs"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ldinihyu
Description = "Support for Software Bus"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ldinihyu
DisplayName = "Software Bus Support"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ldinihyu
ErrorControl = "1"

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ldinihyu
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ldinihyu
Type = "20"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ldinihyu\Parameters
ServiceDll = "{malware path and file name}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\ldinihyu\Parameters
ServiceMain = "DllRegisterServer"

It adds the following registry keys to install itself as a Browser Helper Object (BHO):

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{89A25120-6FF4-8EC7-3CAE-0F8F3CC19CC2}

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\ldinihyu

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CLASSES_ROOT\Dixzqxsj

HKEY_CLASSES_ROOT\CLSID\{89A25120-6FF4-8EC7-3CAE-0F8F3CC19CC2}

It adds the following registry entries:

HKEY_CLASSES_ROOT\Dixzqxsj
(Default) = "{89A25120-6FF4-8EC7-3CAE-0F8F3CC19CC2}"

HKEY_CLASSES_ROOT\CLSID\{89A25120-6FF4-8EC7-3CAE-0F8F3CC19CC2}\
InprocServer32
(Default) = "{malware path and file name}"

HKEY_CLASSES_ROOT\CLSID\{89A25120-6FF4-8EC7-3CAE-0F8F3CC19CC2}\
ProgID
(Default) = "Dixzqxsj"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
ShellIconOverlayIdentifiers\Enhanced Storage
(Default) = "{89A25120-6FF4-8EC7-3CAE-0F8F3CC19CC2}"

NOTES:
It uses Windows Task Scheduler to create a scheduled task to automatically execute itself.

  SOLUTION

Minimum Scan Engine: 9.200
FIRST VSAPI PATTERN FILE: 8.890.04
FIRST VSAPI PATTERN DATE: 06 Apr 2012
VSAPI OPR PATTERN File: 8.891.00
VSAPI OPR PATTERN Date: 07 Apr 2012

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

Scan your computer with your Trend Micro product and note files detected as TROJ_RUDLIN.AE

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_CLASSES_ROOT\CLSID
    • {89A25120-6FF4-8EC7-3CAE-0F8F3CC19CC2}
  • In HKEY_CLASSES_ROOT
    • Dixzqxsj
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects
    • {89A25120-6FF4-8EC7-3CAE-0F8F3CC19CC2}
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • ldinihyu

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\ShellIconOverlayIdentifiers\Enhanced Storage
    • (Default) = "{89A25120-6FF4-8EC7-3CAE-0F8F3CC19CC2}"

Step 6

Delete the Scheduled Tasks added by this malware/grayware

[ Learn More ]

Step 7

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