RE: "Code Red" worm questions

[Eric Chien <ecchien () yahoo com>]

Here are my DRAFT notes that may eventually appear on Symantec's threat 
info sites.

...Eric

The CodeRed worm affects systems running Microsoft Index Server 2.0 or the 
Windows 2000 Indexing service. The worms uses a known buffer overflow 
contained in ISAPI.DLL. Information and a patch regarding this 
vulnerability can be found at: 
http://www.microsoft.com/technet/security/bulletin/MS01-033.asp. 
Administrators are encouraged to apply this patch to prevent infection from 
this worm and other unauthorized access.

The worm sends its code via a HTTP request. This code exploits the buffer 
overflow causing the worm to be executed on the system. The code is not 
saved as a file, but injected and executed directly from memory. Patching 
ones system and rebooting will remove the worm and prevent further infection.

In addition to seeking out new hosts to attack, the worm may attempt a 
denial of service attack. Also, the worm creates multiple threads (many of 
which simply sleep), which can cause instability of the system.

Also Known As: W32/Bady

Category: Worm

Infection Length: 3569

Threat Assessment:

[Medium] [Medium] [Low]
Wild:
Medium Damage:
Medium Distribution:
Low

Wild:
Number of infections: More than 1000
Number of sites: More than 10

Damage:
Payload:
Degrades performance: Will spawn multiple threads and utilize bandwidth.
Causes system instability: Will spawn multiple threads.

Distribution:
Target of infection: Unpatched systems running Microsoft Index 2.0 or 
Windows 2000 Indexing Service

Technical description:

The worm sends its code as an HTTP request. The HTTP request exploits the 
buffer overflow causing the worm to be executed on the system. The 
malicious code is not saved as a file but injected and executed directly 
from memory.

Once executed, the worm creates an empty file c:\notworm as a marker that 
the initial main thread has occured.

New threads are then continuously created. The first 100 threads to attempt 
to exploit more systems by targetting random IP addresses, if the date is 
before the 20th. The worm will not make such HTTP requests to the IP 
address of 127.*.*.* thus, avoiding the loopback address. However, systems 
can become infected again.

Further threads cause webpages to appear to be defaced if the system's 
default language US English. First, the thread sleeps 2 hours and then 
hooks a function, which responds to HTTP requests. Instead of returning the 
proper webpage, the worm returns its own HTML.

The HTML displays:

Welcome to http:// www.worm.com !

Hacked By Chinese!

This hook lasts for 10 hours and then is removed. However, new threads that 
are created can then rehook the function.

Also, if the date is between the 20th and 28th, the worm attempts a Denial 
of Service attack on a particular IP address by sending large amounts of 
junk data to a specific high port.

Finally, if the date is greater than the 28th, the worm's threads simply 
are directed into an infinite sleep.

The continual thread creation (many of which simply sleep) can cause system 
instability.

Removal instructions:

To remove the worm obtain and apply the patch located at 
http://www.microsoft.com/technet/security/bulletin/MS01-033.asp and restart 
the system.
The file c:\notworm can also be deleted.




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