F-Secure Virus Descriptions : Tettona
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++.
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 è infettato dal virus Fralì.
Certo che devi essere proprio un pirlone,
per esserti fatto fregare dal mio stupidissimo worm.
Va bè,và,non ti preoccupare,oggi non sono in vena di cattiverie,
ed è anche un giorno festivo per me.
Buona giornata..
by 4nt4R35
F-Secure Anti-Virus detects the worm with the latest updates.
[Analysis: Eugene Kaspersky; KL; June 2002]
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