Email-Worm.Win32.Dumaru

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

This family of email worms includes I-Worm.Dumaru.b, I-Worm.Dumaru.c. It spreads via the Internet in the form of a file attached to infected messages. It installs a variety of Trojan components on the infected computer.

The worm is only activated if the user launches the infected file by double-clicking on the attachment. Upon launch of the infected file the worm installs itself in the system and launches the replication procedure.

The worm is a Windows PE EXE file compressed using UPX. The size of the compressed file is approximately 9KB and the size of the decompressed file approximately 32KB.

Installation
The worm copies itself under the name load32.exe and vxdmgr32.exe to the Windows system directory and registers one file in the Auto-run key of the system registry:

HKLMSoftwareMicrosoftWindowsCurrentVersionRun



  load32 = %windir%%system%load32.exe

The worm creates a copy of itself in the Windows directory with the name dllreg.exe and installs to this location the file winrdv.exe (approximately 8KB), a backdoor controlled via IRC. Kaspersky Anti-Virus detects this component as Backdoor.Dumador.c (Backdoor.Small.d). This will be used to connect to the author of the worm via IRC in order to receive commands.

Sending messages
The worm searches for *.TBB, *.ABD, *DBX, *.HTML, *.HTM, *.WAB files in all directories on all accessible local disks. It detects lines which are email addresses in these files, and sends infected messages to these addresses.
The worm also creates the file winload.log in the Windows directory and writes the email addresses which infected messages are being sent to to this file.

Infected messages have the Send address as: security@microsoft.com

Message subject:

Use this patch immediately !

Message body:

Dear friend , use this Internet Explorer patch now! There are dangerous virus in the Internet now! More than 500.000 already infected!

Attachment:

patch.exe

In order to send messages, the worm uses a direct connection to the SMTP server, giving a return address of admin@duma.gov.ru. This means that mail scanner notification that the worm has been detected in messages will be sent to this address.

Infection of files
The worm infects executable files in the root directories of all accessible local disks from C: to Z:. To do this it uses NTFS alternate data streams, a method which was first employed by the Stream virus in 2000.

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