PE_ZORI.A

May 21, 2013
 ALIASES:

Virus:Win32/Zori.A (Microsoft); Generic Packed.e (McAfee); W32.Zori.A (Symantec); Virus.Win32.Zori.a (Kaspersky); Virus.Win32.Zori.a (v) (Sunbelt); Win32/PEPatch.I (AVG)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 REPORTED INFECTION:

  • Threat Type: File infector

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This file infector arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size:

1,336,696 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

21 May 2013

Arrival Details

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

  • %System%\svchostv\svchostv\vshell1a\{malware file name}
  • %System%\svchostv\svchostv\vshell1a\{malware file name}.bin

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

It creates the following folders:

  • %System%\SVCHOSTV\SVCHOSTV\Vshell1A
  • %System%\SVCHOSTV
  • %System%\SVCHOSTV\SVCHOSTV

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

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
SVHOST = "%System%\SVCHOSTV\SVCHOST.EXE"

Other System Modifications

This file infector deletes the following files:

  • %System%\svchostv\svchostv\vshell1a\{malware file name}.bin
  • %Temp%\scsC.tmp
  • %Temp%\scsF.tmp

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

Dropping Routine

This file infector drops the following files:

  • %System%\svchostv\svchostv\vshell1a\{malware file name}.log
  • %System%\SVCHOSTV\SVCHOST.EXE

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

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

Restart in Safe Mode

[ Learn More ]

Step 3

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
    • SVHOST = "%System%\SVCHOSTV\SVCHOST.EXE"

Step 4

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%\svchostv\svchostv\vshell1a\{malware file name}.log
  • %System%\SVCHOSTV\SVCHOST.EXE

Step 5

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %System%\SVCHOSTV\SVCHOSTV\Vshell1A
  • %System%\SVCHOSTV
  • %System%\SVCHOSTV\SVCHOSTV

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as PE_ZORI.A. 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%\svchostv\svchostv\vshell1a\{malware file name}.bin
  • %Temp%\scsC.tmp
  • %Temp%\scsF.tmp


Did this description help? Tell us how we did.