1. Symantec/
  2. Security Response/
  3. CodeRed Worm

CodeRed Worm

Risk Level 2: Low

July 16, 2001
February 13, 2007 11:36:53 AM
Also Known As:
W32/Bady, I-Worm.Bady, Code Red, CodeRed, W32/Bady.worm
Systems Affected:
Microsoft IIS
CVE References:
CVE-2001-0500 CVE-2001-0506

The worm sends its code as an HTTP request. The HTTP request exploits a known buffer-overflow vulnerability, which allows the worm to run on your computer. The malicious code is not saved as a file, but is inserted into and then run directly from memory.

Once run, the worm checks for the file, C:\Notworm. If this file exists, the worm does not run and the thread goes into an infinite sleep state.

If the C:\Notworm file does not exist, then new threads are created. If the date is before the 20th of the month, the next 99 threads attempt to exploit more computers by targeting random IP addresses. To avoid looping back to infect the source computer, the worm will not make HTTP requests to the IP addresses 127.*.*.* .

If the default language of the computer is American English, further threads cause Web pages to appear defaced. First, the thread sleeps for two hours, and then hooks a function, which responds to the HTTP requests. Instead of returning the correct Web page, the worm returns its own HTML code.

The HTML displays:

Welcome to http:// www.worm.com !
Hacked By Chinese!

This hook lasts for 10 hours and is then removed. However, re-infection or other threads can rehook the function.

Two versions of this worm have been in the wild. The second version does not cause the Web pages to be defaced.

Also, if the date is between the 20th and 28th of the month, the active threads then attempt a Denial of Service (DoS) attack on a particular IP address, by sending large amounts of junk data to port 80 (Web service) of, which was www.whitehouse.gov. This IP address has been changed and is no longer active.

Finally, if the date is later than the 28th of the month, the worm's threads are not run, but are directed into an infinite sleep state. This multiple-thread creation can cause computer instability.

  • If you are running Microsoft FrontPage or a similar program used to design Web pages, IIS may be installed on your computer.
  • For additional information, including the string that is added to the IIS log files, go to the CERT Coordination Center page at:


  • Hewlett-Packard Jet Direct cards listening on port 80 may also suffer a DoS.


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: Eric Chien
Summary| Technical Details| Removal

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