Welyah

Classification

Malware

Worm

W32

Welyah, I-Worm.Welyah

Summary

Welyah is a mass-mailer worm that is 110 kilobytes in size and was written in Visual Basic.

The worm utilises it's own SMTP engine so it does not depend on Outlook for email sending. The recipient addresses are collected from different files in the system, e.g: *.wab files (Windows Address Book), *.mbx (Mailbox).

Removal

Automatic action

Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

Find out more
Knowledge Base

Find the latest advice in our Community Knowledge Base.

Product Manual

See the manual for your F-Secure product on the Help Center.

Contact Support

Chat with or call an expert for help.

Submit a sample

Submit a file or URL for further analysis.

Technical Details

Messages sent by Welyah look like this:

The attachment name is disguised as a text file but it has .pif extension that is not visible because of the many space characters before it.

The worm also uses the IFRAME vulnerabilty that makes Outlook to execute the attachment automatically. More information on the vulnerabilty can be found at https://www.microsoft.com/windows/ie/downloads/critical/q323759ie/default.asp

When the attachment in executed it copies itself to the Windows directory as 'Winl0g0n.exe' and adds it to the runkeys in the registry as

'[HKLM]\Software\Microsoft\Windows\CurrentVersion\Run\Winl0g0n'

so the worm will be started when Windows starts up.

Date Created: -

Date Last Modified: -