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TROJ_SIREFEF.VRX

November 08, 2012
 ALIASES:

TrojanDropper:Win32/Sirefef.B (Microsoft); W32/Sality.gen.z (McAfee); W32.Sality.AE (Symantec); Virus.Win32.Virut.ce (v) (Sunbelt)

 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:

195,584 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

08 Nov 2012

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 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\.netbt

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\policies\
system

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center\Svc

HKEY_LOCAL_MACHINE\Software\Classes\
Interface\{63c86e33-ae08-09e4-4ace-e515e7d0491a}

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
UacDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center\Svc
AntiVirusOverride = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center\Svc
AntiVirusDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center\Svc
FirewallDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center\Svc
FirewallOverride = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center\Svc
UpdatesDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center\Svc
UacDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
Interface\{63c86e33-ae08-09e4-4ace-e515e7d0491a}
u = "131075"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\.netbt
Type = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\.netbt
Start = "3"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\.netbt
ImagePath = "\*"

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = "2"

(Note: The default value data of the said registry entry is 2.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
AntiVirusOverride = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
AntiVirusDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
FirewallDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
FirewallOverride = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
UpdatesDisableNotify = "1"

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
system
DisableTaskMgr = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
system
DisableRegistryTools = "1"

Dropping Routine

This Trojan drops the following files:

  • ACPI#PNP0303#2&da1a3ff&0\L
  • ACPI#PNP0303#2&da1a3ff&0\L\lauljbdm
  • ACPI#PNP0303#2&da1a3ff&0\{1B372133-BFFA-4dba-9CCF-5474BED6A9F6}
  • ACPI#PNP0303#2&da1a3ff&0\U

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

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

Restart in Safe Mode

[ Learn More ]

Step 3

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.

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
    • .netbt
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\policies
    • system
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • Svc
  • In HKEY_LOCAL_MACHINE\Software\Classes\Interface
    • {63c86e33-ae08-09e4-4ace-e515e7d0491a}

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\Security Center
    • UacDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center\Svc
    • AntiVirusOverride = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center\Svc
    • AntiVirusDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center\Svc
    • FirewallDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center\Svc
    • FirewallOverride = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center\Svc
    • UpdatesDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center\Svc
    • UacDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Interface\{63c86e33-ae08-09e4-4ace-e515e7d0491a}
    • u = "131075"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\.netbt
    • Type = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\.netbt
    • Start = "3"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\.netbt
    • ImagePath = "\*"

Step 6

Restore this modified 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\CurrentVersion\Explorer\Advanced
    • From: Hidden = "2"
      To: Hidden = ""2""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • AntiVirusOverride = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • AntiVirusDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • FirewallDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • FirewallOverride = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • UpdatesDisableNotify = "1"

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.
  • ACPI#PNP0303#2&da1a3ff&0\L
  • ACPI#PNP0303#2&da1a3ff&0\L\lauljbdm
  • ACPI#PNP0303#2&da1a3ff&0\{1B372133-BFFA-4dba-9CCF-5474BED6A9F6}
  • ACPI#PNP0303#2&da1a3ff&0\U

Step 8

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