minimal-minimal

W32/Dasher.worm

W32/Dasher.worm

Threat Detail

  • Malware Type: Virus
  • Malware Sub-type: Worm
  • Protection Added: 2005-12-15

This is a virus detection. Viruses are programs that self-replicate recursively, meaning that infected systems spread the virus to other systems, which then propagate the virus further. While many viruses contain a destructive payload, it's quite common for viruses to do nothing more than spread from one system to another.


Minimum Engine

5400.1158

File Length

Varies

Description Added

2005-12-15

Description Modified

2005-12-15

Malware Proliferation

fpo-ti-severity-legend logo-new-mcafee

W32/Dasher.worm is a self-extractor RAR archive that will try to exploit Microsoft Windows Vulnerabilities in MSDTC and COM+ (MS05-051 ) also Vulnerabilities in Microsoft SQL server (MS02-056 ) after deploying itself on a vulnerable host.

Files Added

  • %WINDIR%\temp\sqlscan.bat (306 Bytes)
  • %WINDIR%\temp\sqlrep.exe (20,992 Bytes)
  • %WINDIR%\temp\sqltob.exe (7,200 Bytes)
  • %WINDIR%\temp\sqlexp.exe (7,712 Bytes)
  • %WINDIR%\temp\sqlscan.exe (19,968 Bytes)
  • %WINDIR%\temp\Temp.txt
  • %WINDIR%\temp\log.txt

Registry

The following registry keys are written:

  • hkey_local_machine\software\microsoft\windows\currentversion\run
    \windows update="%WINDIR%\Temp\Sqltob.exe"
  • hkey_current_user\software\winrar sfx\c%%windows%temp%="
    %WINDIR%\Temp\"

Hence, sqltob.exe will run every time the infected host starts.

All Users:

Please use the following instructions for all supported versions of Windows to remove threats and other potential risks:

1.Disable System Restore .

2.Update to current engine and DAT files for detection and removal.

3.Run a complete system scan.

Modifications made to the system Registry and/or INI files for the purposes of hooking system startup, will be successfully removed if cleaning with the recommended engine and DAT combination (or higher).

1. Please go to the Microsoft Recovery Console and restore a clean MBR.

On windows XP:

Insert the Windows XP CD into the CD-ROM drive and restart the computer.
When the "Welcome to Setup" screen appears, press R to start the Recovery Console.
Select the Windows installation that is compromised and provide the administrator password
Issue 'fixmbr' command to restore the Master Boot Record
Follow onscreen instructions
Reset and remove the CD from CD-ROM drive.


On Windows Vista and 7:

Insert the Windows CD into the CD-ROM drive and restart the computer.
Click on "Repair Your Computer"
When the System Recovery Options dialog comes up, choose the Command Prompt.
Issue 'bootrec /fixmbr' command to restore the Master Boot Record
Follow onscreen instructions
Reset and remove the CD from CD-ROM drive.

The worm scans for vulnerable hosts on port (TCP/1025 - Microsoft RPC) and will send the shellcode if one is found.

The worm scans for hosts on port (TCP/445 - Microsoft DS) and will attempt to use COM+ exploit upon them.

The worm scans for vulnerable hosts on port (TCP/1433 - Microsoft SQL).

Every time sqltob.exe runs, it creates a thread for sqlreq.exe which would call sqlscan.exe . Each single instance of sqlscan.exe will attempt to scan 65278 hosts using TCP/SYN packets and store the result in Results.txt

Attempted IPs

58.X.Y.Y

54.X.Y.Y 

Where X is an octet that will be selected randomly every time the worm starts scanning for 65278 hosts, and Y is a number that will be increased sequentially (from 1-254).

(Worm might scan other IP ranges other than 58.0.0.0/8 and 54.0.0.0/8)

The worm creates the following network connection(s):

SqlExp.exe server:58.X.Y.Y Source Port (TCP/6000) Destination Port (TCP/1025)

SqlExp.exe server:54.X.Y.Y Source Port (TCP/6000) Destination Port (TCP/1025) 

Source port blocking or scanning of port 6000 could be used for detection or blocking of this worm. 

Infected hosts attempt a connection to 222.240.219.143 on TCP port 53 (DNS)

(Worm might attempt to connect to other hosts on port 53)