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Discovered: December 22, 2003
Updated: February 13, 2007 12:15:27 PM
Type: Worm
Systems Affected: Windows

W32.Cissi.A@mm is a mass-mailing worm, which also contains backdoor functionality to connect to an IRC server. This worm can also wait for commands.

W32.Cissi.A@mm can spread over the network using the NetBIOS protocol. It can spread to systems that do not have passwords or to ones that have simple passwords.

The worm is written in Delphi and is packed with UPX.

Antivirus Protection Dates

  • Initial Rapid Release version December 23, 2003
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version December 23, 2003
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date December 23, 2003

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Neal Hindocha

Discovered: December 22, 2003
Updated: February 13, 2007 12:15:27 PM
Type: Worm
Systems Affected: Windows

When W32.Cissi.A@mm is executed, it performs the following actions:

  1. Copies of itself as %System%\Cissi.exe.

    Note: %System% is a variable. The Worm locates the System folder and copies itself to that location. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

  2. If the operating system is Windows 95/98/Me, the worm modifies the System.ini so that the worm is executed each time you restart the computer.

  3. If the operating system is Windows NT/2000/XP/2003, the worm will contain code to modify the Windows registry so that it will run when you start Windows, However, due to what appears to be a bug in the code, information will not be written to the Windows registry.

  4. May attempt to add itself to the Startup group in the start menu by creating an additional copy of itself. The worm has the following paths hardcoded inside its viral body:
    • \Documents and Settings\All Users\Start Menu\Programs\Startup
    • \WINDOWS\Start Menu\Programs\Startup
    • \WINNT\Profiles\All Users\Start Menu\Programs\Startup

      However, during testing, the worm never successfully created a copy of itself in any of these locations.

Once the worm has created the copy of itself as %Stem%\Cissi.exe and made the changes described in steps 2 through 4, the worm will attempt to spread.

W32.Cissi.A@mm is a multi-threaded worm, which means that it can simultaneously perform several actions on the system.

W32.Cissi.A@mm will create a thread that attempts to join a predefined channel on the IRC server, irc.undernet.org. The worm will connect to the server using a randomly generated nickname, and will attempt to connect to the server on port 6667. Once connected, the worm will wait for commands from the server.

Network Spreading
W32.Cissi.A@mm will create a thread designated to finding computers that can be infected. The worm will use the NetBIOS protocol, and the connection from the system will therefore go to NetBIOS ports 135,139, and 445. The worm will connect to randomly generated IP addresses, and first it will try to connect without using any password. If this fails, the worm will try the following passwords.
  • 1234
  • password
  • 6969
  • harley
  • 123456
  • golf
  • pussy
  • mustang
  • 1111
  • shadow
  • 1313
  • fish
  • 5150
  • 7777
  • qwerty
  • baseball
  • 2112
  • letmein
  • 12345678
  • 12345
  • ccc
  • admin
  • Admin
  • Password
  • 123
  • 1234567
  • 123456789
  • 654321
  • 54321
  • 111
  • 000000
  • abc
  • 11111111
  • 88888888
  • pass
  • passwd
  • database
  • abcd
  • abc123
  • sybase
  • 123qwe
  • server
  • computer
  • Internet
  • super
  • 123asd
  • ihavenopass
  • godblessyou
  • enable
  • 2002
  • 2003
  • 2600
  • alpha
  • 110
  • 111111
  • 121212
  • 123123
  • 1234qwer
  • 123abc
  • 007
  • aaa
  • patrick
  • pat
  • administrator
  • root
  • sex
  • god
  • foobar
  • secret
  • test
  • test123
  • temp
  • temp123
  • win
  • asdf
  • oracle'pwd
  • qwer
  • yxcv
  • zxcv
  • home
  • xxx
  • owner
  • login
  • Login
  • pw123
  • love
  • mypc
  • mypc123
  • admin123
  • mypass
  • mypass123
  • 901100

The user names this worm tries are:
  • Guest
  • Administrator
  • Owner
  • Root

If the worm succeeds in connecting to the remote system, it creates a copy of itself on that system. The worm also attempts to schedule a job so that the newly inserted viral file is automatically executed on the remote system.

The worm can also enumerate mapped drives on the system, and then create a copy of itself on any mapped drive where it has sufficient access rights.

W32.Cissi.A@mm is a mass-mailer. The email message that this worm sends has the following characteristics.

Subject : The subject will be randomly chosen from the following list:
  • Heres a poem for you
  • Ive written a poem for you
  • Love poems for you :)
  • Look what i wrote for you
  • Poems for you
  • Roses are red,
  • You are mine,
  • I love you until im dead,
  • It will all be fine.
  • I do miss you
  • I do love you
  • what you want me to do?
  • I never want to go.
  • Where did you run?
  • Where did you hide?
  • I stand here undone
  • I stand here inside
  • How could u do that
  • Why did you say that
  • How do you feel inside
  • I wish i just could hide

Attachment: The attachment will be one of the following:
  • LovePoem.pif
  • Poem_collection.pif
  • Zipped_poems.exe
  • My Poems.txt.exe
  • Poems.pif
  • Sad Stories and Poems.pif
  • My Story.pif
  • The Poems.pif
  • Poems for you.pif
  • Only Poems.txt.pif

The worm will scan the system for files that have the following extensions.
  • .htt
  • .rtf
  • .doc
  • .xls
  • .ini
  • .mdb
  • .txt
  • .htm
  • .html
  • .wab
  • .pst
  • .fdb
  • .cfg
  • .ldb
  • .eml
  • .abc
  • .ldif
  • .nab
  • .adp
  • .mdw
  • .mda
  • .mde
  • .ade
  • .sln
  • .dsw
  • .dsp
  • .vap
  • .php
  • .asp
  • .shtml

From every file that has a matching extension, the worm attempts to find email addresses. The email addresses will be saved in the file, %System%\Cissi.dll.

Following this, the worm will query the default DNS server on the system for the Mail eXchange (MX ) record. The MX record normally contains the IP address for the mail server. The worm will use this email server to send email messages.

Note: This worm contains several bugs, and repeated crashes and slowdowns were seen when running this threat inside a test environment.


Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.

Writeup By: Neal Hindocha

Discovered: December 22, 2003
Updated: February 13, 2007 12:15:27 PM
Type: Worm
Systems Affected: Windows

The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

  1. Disable System Restore (Windows Me/XP).
  2. Update the virus definitions.
  3. Run a full system scan and delete all the files detected as W32.Cissi.A@mm.
  4. Delete the value that was added to the System.ini (Windows 95/98/Me).
For specific details on each of these steps, read the following instructions.

1. Disabling System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.

Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.

For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:
Note: When you are completely finished with the removal procedure and are satisfied that the threat has been removed, re-enable System Restore by following the instructions in the aforementioned documents.

For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article, "Antivirus Tools Cannot Clean Infected Files in the _Restore Folder ," Article ID: Q263455.

2. Updating the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:
  • Running LiveUpdate, which is the easiest way to obtain virus definitions: These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate).
  • Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater).

    The Intelligent Updater virus definitions are available: Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

3. Scanning for and deleting the infected files
  1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
  2. Run a full system scan.
  3. If any files are detected as infected with W32.Cissi.A@mm, click Delete.
4. Deleting the value added to the System.ini file (Windows 95/98/Me)
If you are running Windows 95/98/Me, follow these steps:
  1. The function you perform depends on your operating system:
    • Windows 95/98: Go to step B.
    • Windows Me: If you are running Windows Me, the Windows Me file-protection process may have made a backup copy of the System.ini file that you need to edit. If this backup copy exists, it will be in the C:\Windows\Recent folder. Symantec recommends that you delete this file before continuing with the steps in this section. To do this:
      1. Start Windows Explorer.
      2. Browse to and select the C:\Windows\Recent folder.
      3. In the right pane, select the Win.ini file and delete it. The System.ini file will be regenerated when you save your changes to it in step F.

  2. Click Start, and then click Run.
  3. Type the following, and then click OK.

    edit c:\windows\system.ini

    (The MS-DOS Editor opens.)

    NOTE: If Windows is installed in a different location, make the appropriate path substitution.

  4. In the [boot] section of the file, look for a line similar to:

    shell = Explorer.exe %system%\CISSI.EXE

  5. If this line exists, delete everything to the right of Explorer.exe.

    When you are done, it should look like:

    shell = Explorer.exe

  6. Click File, and then click Save.
  7. Click File, and then click Exit.

Writeup By: Neal Hindocha