Email-Worm.Win32.Tettona

Parent class: VirWare

Viruses and worms are malicious programs that self-replicate on computers or via computer networks without the user being aware; each subsequent copy of such malicious programs is also able to self-replicate. Malicious programs which spread via networks or infect remote machines when commanded to do so by the “owner” (e.g. Backdoors) or programs that create multiple copies that are unable to self-replicate are not part of the Viruses and Worms subclass. The main characteristic used to determine whether or not a program is classified as a separate behaviour within the Viruses and Worms subclass is how the program propagates (i.e. how the malicious program spreads copies of itself via local or network resources.) Most known worms are spread as files sent as email attachments, via a link to a web or FTP resource, via a link sent in an ICQ or IRC message, via P2P file sharing networks etc. Some worms spread as network packets; these directly penetrate the computer memory, and the worm code is then activated. Worms use the following techniques to penetrate remote computers and launch copies of themselves: social engineering (for example, an email message suggesting the user opens an attached file), exploiting network configuration errors (such as copying to a fully accessible disk), and exploiting loopholes in operating system and application security. Viruses can be divided in accordance with the method used to infect a computer:

• file viruses
• boot sector viruses
• macro viruses
• script viruses

Any program within this subclass can have additional Trojan functions. It should also be noted that many worms use more than one method in order to spread copies via networks.

Class: Email-Worm

Email-Worms spread via email. The worm sends a copy of itself as an attachment to an email message or a link to its file on a network resource (e.g. a URL to an infected file on a compromised website or a hacker-owned website). In the first case, the worm code activates when the infected attachment is opened (launched). In the second case, the code is activated when the link to the infected file is opened. In both case, the result is the same: the worm code is activated. Email-Worms use a range of methods to send infected emails. The most common are: using a direct connection to a SMTP server using the email directory built into the worm’s code using MS Outlook services using Windows MAPI functions. Email-Worms use a number of different sources to find email addresses to which infected emails will be sent: the address book in MS Outlook a WAB address database .txt files stored on the hard drive: the worm can identify which strings in text files are email addresses emails in the inbox (some Email-Worms even “reply” to emails found in the inbox) Many Email-Worms use more than one of the sources listed above. There are also other sources of email addresses, such as address books associated with web-based email services.

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Platform: Win32

Win32 is an API on Windows NT-based operating systems (Windows XP, Windows 7, etc.) that supports execution of 32-bit applications. One of the most widespread programming platforms in the world.

Description

Technical Details

This is the worm virus 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 of length (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 Bodies are:

 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.

Attached files:

   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.

Installing

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

HKLMSoftwareMicrosoftWindowsCurrentVersionRun DllManager = %windir%dllmgr32.exe

The worm then displays fake error message:

 Error
  VBRUN49.DLL not found!

Spreading

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.

Backdoor

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

Payload

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

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