Tettona

Classification

Malware

Worm

W32

Tettona, IWorm_Tettona, I-Worm.Tettona

Summary

Tettona is the worm spreading via the Internet being attached to infected emails. The worm also has backdoor routine.

The worm itself is Windows PE EXE file about 35Kb long (compressed by Petite, decompressed size - about 75Kb), written in Microsoft Visual C++.

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.

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Technical Details

The texts and attached file names in infected messages are different, they depend on current date and Italian language support:

Subjects are:

 Incredible..

Incredibile..

Urgente! (vedi allegato)

Qualsiasi cosa fai,falla al meglio.

The message body begins with "Hello," or "Ciao," text, then goes:

see this interesting file.
okkio all'allegato ;-)
devi assolutamente vedere il file che ti ho allegato.
apri subito l'allegato,e' MOLTO interessante.

The message body is completed with "A presto..." or "Bye." text.

Attachment names can be:

 tettona.exe

euro.exe

tattoo.exe

The worm activates from infected email only in case a user clicks on attached file. The worm then installs itself to the system, runs spreading routine and backdoor.

While installing the worm copies itself to Windows directory with the DLLMGR32.EXE name and registers that file in system registry auto-run key:

HKLM\Software\Microsoft\Windows\CurrentVersion\Run
 DllManager = %windir%\dllmgr32.exe

The worm then displays a fake error message:

Error
 VBRUN49.DLL not found!

To send infected messages the worm uses direct connection to default SMTP server, then opens WAB database (Windows Address Book) and sends messages to all addresses found in there.

The backdoor procedure opens connection on port 5001 and listens to the "master". Then it processes following instructions:

"HELO" - replies with "Hello, guy" text
"SCAN" - scans all directories and reports dir/files in there (like remote DIR command)
"EXEC" - runs specified file
"UNINST" - removes itself from the system, including registry "Run" key.
"VIEW" - displays to "master" specified file
"DOWN" - downloads to "master" specified file

On January 12th the worm displays the message:

Hello,
 Ciao,
 il tuo computer - infettato dal virus Fral.
 Certo che devi essere proprio un pirlone,
 per esserti fatto fregare dal mio stupidissimo worm.
 Va b-,v,non ti preoccupare,oggi non sono in vena di cattiverie,
 ed - anche un giorno festivo per me.
 Buona giornata..
 by 4nt4R35

F-Secure Anti-Virus detects the worm with the latest updates.

Date Created: -

Date Last Modified: -