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
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.Read more
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 first known modern Internet Worm discovered "in the wild." This computer worm is a kind of virus program that, while spreading its copies, does not infect disk files as the main target, but replicates its copies by sending itself via the Internet as an attachment in e-mail messages. The worm was posted by somebody (maybe by the worm's author) to several news servers in January 1999, and then in few days, it was discovered "in the wild" in Europe and continued spreading.
The worm arrives as an attachment in an e-mail as a HAPPY99.EXE file. When an infected attachment is executed and gains control, the worm displays a funny firework in the program's window to hide its malicious nature. During this, it installs itself in the system, hooks sendings to the Internet, converts its code to the attachment and appends it to the messages. As a result the worm, when it is installed into the system, is able to spread its copies to all the addresses the messages are sent to.
While installing, the worm affects files in the Windows system directory only. It creates the SKA.EXE and SKA.DLL files in there, copies the WSOCK32.DLL to the newly created WSOCK32.SKA and patches the original WSOCK32.DLL file to hook e-mail sending calls.
Removal and Protection
If the worm is detected in your system, you can easily get rid of it just by deleting the SKA.EXE and SKA.DLL files in the system Windows directory. You also should delete the WSOCK32.DLL file and replace it with the WSOCK32.SKA original file. The original HAPPY99.EXE file should also be located and deleted.
To protect your computer from re-infection, you need only set the "Read-Only" attribute for the WSOCK32.DLL file. The worm does not pay attention to the Read-Only mode, and fails to patch the file. This trick was discovered by Peter Szor at DataFellows (http://www.datafellows.com).
Please Remember
Do not open and do not execute the HAPPY99.EXE file that you have received as an attachment in any message if you receive it from an untrusted or unknown source. You should also remember that the files you have accessed from the Internet can contain malicious code that may infect your computer, destroy data, send confidential files to through the Internet, or install spy programs to monitor your computer from a remote host.
Opening MS Office files with disabled VirusProtection and executing untrusted executable files is extremely risky. You should keep this in mind each time you see an attachment to incoming message.
Technical Details
The worm arrives exactly as a 10.000-byte executable HAPPY99.EXE file. This file has Win32 Portable Executable (PE) internal structure. The worm installs itself into the Win95/98 systems and continues spreading with no problems. Under WinNT, it is not able to spread because of bugs.
The worm contains text strings, some of them are encrypted:
Is it a virus, a worm, a trojan? MOUT-MOUT Hybrid (c) Spanska 1999. Happy New Year 1999 !! begin 644 Happy99.exe end Ska.exe liste.ska wsock32.dll Ska.dll Ska.exe
When the HAPPY99.EXE file is executed, the worm copies itself to the Windows system directory with the SKA.EXE name and drops the additional SKA.DLL file in the same directory. The SKA.DLL is stored in the main EXE file (HAPPY99.EXE) in encrypted and lite-packed form.
The worm then copies the WSOCK32.DLL to the WSOCK32.SKA name (makes a "backup") and patches the WSOCK32.DLL file. If the WSOCK32.DLL is in use and cannot be opened for writing, the worm creates a new key in the system registry to run its dropper during the next rebooting:
HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunOnce=SKA.EXE
The WSOCK32.DLL patch consists of a worm initialization routine and two redirected exports. The initialization routine is just a small piece of worm code - just 202 bytes. It is saved to the end of WSOCK32.DLL code section (".text" section). The WSOCK32.DLL has enough space for that, and the size of WSOCK32.DLL is not increased during infection. Then the worm patches the WSOCK32.DLL export tables so that two functions ("connect" and "send") will point to the worm initialization routine at the end of WSOCK32.DLL code section.
When a user is connecting to the Internet the WSOCK32.DLL is activated, and the worm hooks two events: connection and data sending. The worm monitors the e-mail and news ports (25 and 119 - smtp and nntp). When it detects a connection on one of these ports, it loads its SKA.DLL library that has two exports: "mail" and "news". Depending on the port number, the worm calls one of these routines, but both of them create a new message, insert UUencoded worm HAPPY99.EXE dropper into it, and send it to an Internet address. The worm also adds its stamp to the kludge header of "infected" messages:
X-Spanska: Yes
While sending infected attachments, the worm stores the recipients' addresses to the LISTE.SKA file in the Windows system directory. This "log" file contains up to 5K of data, and may contain up to about 200 addresses the infected messages were sent to.
Demonstrations of the virus' effects:
|
happy.gif |
Read more
Find out the statistics of the vulnerabilities spreading in your region on statistics.securelist.com