WORM_AUTORUN.BYT

Malware type: Worm

Aliases: No Alias Found

In the wild: No

Destructive: No

Language: English

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

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

Medium

Distribution potential:

Medium

Infection Channel 1 : Propagates via removable drives


Infection Channel 2 : Copies itself in all available physical drives


Description: 

A worm is a malware that is designed to propagate and spread across networks. Worms are known to propagate using one or several of different transmission vectors like email, IRC, network shares, instant messengers (IM), and peer-to-peer (P2P) networks.

Worms do not infect files, but may carry one or more payloads, such as computer security compromise and information theft.

Worms typically modify system settings to automatically start. Users may need to terminate worms before they can be deleted. Also, restoring affected systems may require procedures other than scanning with an antivirus program.

For additional information about this threat, see:

Description created: Sep. 24, 2008 2:53:46 AM GMT -0800


TECHNICAL DETAILS


File type: PE

Memory resident:  Yes

Size of malware: Varies

Details:

This worm creates the following registry entry(ies) to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
Run
kmmsoft = "%System%\revo.exe"

(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 modifies the following registry entry(ies) to hide files with both System and Read-only attributes:

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

(Note: The default value data for the said registry entry is 1.)

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\
Explorer\Advanced
ShowSuperHidden = "0"

(Note: The default value data for the said registry entry is 1.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\
Explorer\Advanced\Folder\Hidden\SHOWALL
CheckedValue = "0"

(Note: The default value data for the said registry entry is 1.)

This worm drops copies of itself in all physical drives. It drops a copy of itself in all removable drives as f.exe. It drops an AUTORUN.INF file to automatically execute dropped copies when the drives are accessed.

The file AUTORUN.INFns the following strings:

;{Garbage}
[AutoRun]
;{Garbage}
open=f.exe
;{Garbage}
shell\open\Command=f.exe
;{Garbage}
shell\open\Default=1
;{Garbage}
shell\explore\Command=f.exe
;{Garbage}

It drops the following file(s):

  • %System%\revo.exe - copy of itself
  • %System%\revo0.dll - also detected as WORM_AUTORUN.BYT

Analysis By: Jasper Manuel


SOLUTION


Minimum scan engine version needed: 8.500

Pattern file needed: 5.559.00

Pattern release date: Sep 22, 2008


Important note: The "Minimum scan engine" refers to the earliest Trend Micro scan engine version guaranteed to detect this threat. However, Trend Micro strongly recommends that you update to the latest version in order to get comprehensive protection. Download the latest scan engine here.

Solution:

Important Windows ME/XP Cleaning Instructions

Users running Windows ME and XP must disable System Restore to allow full scanning of infected computers.

Users running other Windows versions can proceed with the succeeding solution set(s).

Restarting in Safe Mode

This malware has characteristics that require the computer to be restarted in safe mode. Go to this page for instructions on how to restart your computer in safe mode.

Removing Autostart Entries from the Registry

This solution deletes/modifies registry keys/entries added/modified by this malware. Before performing the steps below, make sure you know how to back up the registry and how to restore it if a problem occurs. Refer to this Microsoft article for more information about modifying your computer's registry.

  1. Open Registry Editor. Click Start>Run, type REGEDIT, then press Enter.
  2. In the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>
    Run
  3. In the right panel, locate and delete the entry:
    kmmsoft = "%System%\revo.exe"
  4. (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.)

Restoring Registry Entries

  1. Still in the Registry Editor, in the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>
    Explorer>Advanced
  2. In the right panel, locate the entry:
    Hidden = "2"
  3. Right-click on the value name and choose Modify. Change the value data of this entry to:
    "1"
  4. In the right panel, locate the entry:
    ShowSuperHidden = "0"
  5. Right-click on the value name and choose Modify. Change the value data of this entry to:
    "1"
  6. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows>CurrentVersion>
    Explorer>Advanced>Folder>Hidden>SHOWALL
  7. In the right panel, locate the entry:
    CheckedValue = "0"
  8. Right-click on the value name and choose Modify. Change the value data of this entry to:
    "1"
  9. Close Registry Editor.

Deleting Malware-created AUTORUN.INF/s

  1. Right-click Start then click Search... or Find..., depending on the version of Windows you are running.
  2. In the Named input box, type:
    AUTORUN.INF
  3. In the Look In drop-down list, select a drive, then press Enter.
  4. Select the file, then open using Notepad.
  5. Check if the following lines are present in the file:

    ;{Garbage}
    [AutoRun]
    ;{Garbage}
    open=f.exe
    ;{Garbage}
    shell\open\Command=f.exe
    ;{Garbage}
    shell\open\Default=1
    ;{Garbage}
    shell\explore\Command=f.exe
    ;{Garbage}

  6. If the lines are present, delete the file.
  7. Repeat steps 3 to 6 for AUTORUN.INF files in the remaining removable drives.
  8. Close Search Results.

Running Trend Micro Antivirus

If you are currently running in safe mode, please restart your computer normally before performing the following solution.

Scan your computer with Trend Micro antivirus and delete files detected as WORM_AUTORUN.BYT. To do this, Trend Micro customers must download the latest virus pattern file and scan their computer. Other Internet users can use HouseCall, the Trend Micro online virus scanner.




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