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WORM_FLYSTUD.ERR

October 08, 2012
 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Propagates via removable drives

This worm drops copies of itself in all removable drives. It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

  TECHNICAL DETAILS

File Size:

1,400,709 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

09 Nov 2010

Payload:

Drops files

Installation

This worm creates the following folders:

  • %System%\{Random name1}
  • %System%\{Random name2}
  • %System%\{Random name3}
  • %System%\{Random name4}
  • %User Temp%\E_N4

(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.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

Other System Modifications

This worm deletes the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\TypedURLs

Propagation

This worm drops copies of itself in all removable drives.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

[AutoRun]
open=Recycled.exe
shell\1=´ò¿ª(&O)
shell\1\Command=Recycled.exe
shell\2\=ä¯ÀÀ(&B)
shell\2\Command=Recycled.exe
shellexecute=Recycled.exe

Dropping Routine

This worm drops the following files:

  • %System%\{Random name1}\krnln.fnr - also detected as WORM_FLYSTUD.ERR
  • %System%\{Random name1}\eAPI.fne - also detected as WORM_FLYSTUD.ERR
  • %System%\{Random name1}\dp1.fne - also detected as WORM_FLYSTUD.ERR
  • %System%\{Random name1}\shell.fne - also detected as WORM_FLYSTUD.ERR
  • %System%\{Random name1}\cnvpe.fne - also detected as WORM_FLYSTUD.ERR
  • %System%\{Random name1}\com.run - also detected as WORM_FLYSTUD.ERR
  • %System%\{Random name1}\internet.fne - detected as TROJ_FLYSTUD.EIK
  • %System%\{Random name1}\RegEx.fnr - detected as TROJ_FLYSTUD.EIK
  • %System%\{Random name1}\spec.fne - also detected as WORM_FLYSTUD.ERR
  • %System%\{Random name1}\spec_a.fne - also detected as WORM_FLYSTUD.ERR
  • %System%\{Random name1}\{random filename}.exe - also detected as WORM_FLYSTUD.ERR
  • %User Temp%\E_N4\krnln.fnr - also detected as WORM_FLYSTUD.ERR
  • %User Temp%\E_N4\eAPI.fne - also detected as WORM_FLYSTUD.ERR
  • %User Temp%\E_N4\dp1.fne - also detected as WORM_FLYSTUD.ERR
  • %User Temp%\E_N4\shell.fne - also detected as WORM_FLYSTUD.ERR
  • %User Temp%\E_N4\cnvpe.fne - also detected as WORM_FLYSTUD.ERR
  • %User Profile%\Start Menu\Programs\Startup\{Random file name}.lnk - non-malicious file

(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.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.. %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

NOTES:
WORM_FLYSTUD.ERR

Other Details

Based on analysis of the codes, it has the following capabilities:

It also searches for folders in removable drives then drops copies of itself as {Folder name}.exe. It then sets the attribute of the original folder to Hidden, Read-Only, and System to trick the users into thinking that the dropped copy is the legitimate folder.

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

7.606.01

FIRST VSAPI PATTERN DATE:

09 Nov 2010

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 WORM_FLYSTUD.ERR

    TROJ_FLYSTUD.EIK

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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.  %User Temp%\E_N4

Step 5

Search and delete this file

[ 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. %User Profile%\Start Menu\Programs\Startup\{Random file name}.lnk

Step 6

Search and delete AUTORUN.INF files created by WORM_FLYSTUD.ERR that contain these strings

[ Learn More ]
[AutoRun]
open=Recycled.exe
shell\1=´ò¿ª(&O)
shell\1\Command=Recycled.exe
shell\2\=ä¯ÀÀ(&B)
shell\2\Command=Recycled.exe
shellexecute=Recycled.exe

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_FLYSTUD.ERR. 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 8

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. HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\TypedURLs


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