PE_VIRUX.A-O

October 08, 2012
 Analysis by: Kathleen Notario
 PLATFORM:

Windows 98, ME, NT, 2000, XP, Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: File infector

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This file infector executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

168,960 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

03 Aug 2010

Installation

This file infector drops the following copies of itself into the affected system:

  • %Windows%\system\1sass.exe

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

Autostart Technique

This file infector adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
lsass = %Windows%\system\1sass.exe

Other System Modifications

This file infector adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot\Minimal\
lsass
=

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot\Network\
lsass
=

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\Safeboot\Minimal\
lsass
(default) = Service

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\Safeboot\Network\
lsass
(default) = Service

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%Windows%\\system\\1sass.exe = %Windows%\system\1sass.exe:*:Enabled:1sass

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\AuthorizedApplications\
List
\\??\\%System%\\winlogon.exe = \??\%System%\winlogon.exe:*:enabled:@shell32.dll,-1

File Infection

This file infector infects the following file types:

  • EXE
  • SCR

It avoids infecting files that contain the following strings in their names:

  • WINC
  • WCUN
  • WC32
  • OTSP

Dropping Routine

This file infector drops the following files:

  • %System%\drivers\sysdrv32.sys - detected as HKTL_TCPAGENT

(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 executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

Other Details

This file infector deletes itself after execution.

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI PATTERN File:

7.358.11

VSAPI PATTERN Date:

03 Aug 2010

VSAPI PATTERN Date:

8/3/2010 12:00:00 AM

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

Remove malware files dropped/downloaded by PE_VIRUX.A-O

Step 3

Restart in Safe Mode

[ Learn More ]

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • lsass=%Windows%\system\1sass.exe
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %Windows%\system\1sass.exe=%Windows%\system\1sass.exe:*:Enabled:1sass
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • \??\%System%\winlogon.exe=\??\%System%\winlogon.exe:*:enabled:@shell32.dll,-1

Step 5

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\Control\SafeBoot\Minimal
    • lsass
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot\Network
    • lsass

Step 6

Remove these strings added by the malware/grayware/spyware in the HOSTS file

[ Learn More ]
    "DATA_GENERIC
  • Save the file and close the text editor.

    • Step 7

    Scan your computer with your Trend Micro product to delete files detected as PE_VIRUX.A-O. 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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