Hi -

Here's some more information about the most recent IIS worm, which was
posted to NTBugTraq earlier today.

Hope this helps someone.

Jay

-----Original Message-----
From: Marc Maiffret [mailto:[EMAIL PROTECTED]] 
Sent: Tuesday, July 17, 2001 2:18 PM
To: [EMAIL PROTECTED]
Subject: Initial analysis of the .ida "Code Red" Worm


The following information was researched by Ryan Permeh ([EMAIL PROTECTED]
and Marc Maiffret ([EMAIL PROTECTED] of eEye Digital Security. We would like
to specially thank Matthew Asham of Left Coast Systems Corp and Ken
Eichman of Chemical Abstracts Service for providing us with logs and
needed data to make this analysis possible.

Introduction
------------

On Friday July 13th we received packet logs and information from 2
network administrators that were experiencing large amounts of attacks
targeting the recent .ida vulnerability that eEye Digital Security
discovered
(http://www.eeye.com/html/Research/Advisories/AD20010618.html) on June
18, 2001.

>From the first analysis of the logs that were sent to us we were able 
>to
deduce that in fact it looked as if someone had released a worm for the
..ida vulnerability. Within the logs we could see connection attempts
from over 5 thousand IIS 5 web servers targeting various other IIS web
server and sending a .ida exploit to each of them. Evidence also showed
that compromised hosts were being used to attack other hosts.

We've designated this the .ida "Code Red" worm, because part of the worm
is designed to deface webpages with the text "Hacked by Chinese" and
also because code red mountain dew was the only thing that kept us awake
all last night to be able to disassemble this exploit.

Details
-------
Note: Details are going to be short for now. We plan on releasing a full
analysis of the worm but felt that it was important to get this message
out ASAP as this worm is starting to affect a lot of people.

The standard injection vector is a exploit that uses the .ida buffer
overflow to execute code (as SYSTEM) on vulnerable remote systems.

The worm performs the following on infected systems:
* Spawns 100 threads which are used to scan for new IIS web servers to
infect
* Checks for the existence of c:\notworm and if it is found then it does
not try to propagate itself to other hosts.
* Defaces web pages with the message:
<html><head><meta http-equiv="Content-Type" content="text/html;
charset=English"><title>HELLO!</title></head><bady><hr size=5><font
color="red"><p align="center">Welcome to http://www.worm.com
!<br><br>Hacked By Chinese!</font></hr></bady></html>

Analysis
--------
Note: Again this is a quick brief analysis, more detail will follow.

Upon infection the infected host will spawn 100 threads in a loop. This
loop checks for the existence of c:\notworm and if the file does not
exist then the worm will proceed to start scanning for vulnerable
servers to infect.

The worm does scan for random IP addresses. However, the worm uses the
same seed for "randomization" of IP addresses. This means that each new
infected host will start at the same IP and continue scanning further
down the same track of IP's as every other infected host. The
ramifications of this are severe because this means that hosts early in
this "randomized" IP sequence will be hit over and over as new hosts are
infected. This creates the potential for a denial of service against
early IP addresses in the sequence. Also, evidence has proved that hosts
can be infected multiple times therefore creating a drain on system
resources. However, normal worm operation seems to have a cut off point
as to how many times a host will be re-infected. Early analysis seems to
suggest that the worm has a limit of 3 reinfections however that may
have just been "by chance" in our test scenario.

Other in house tests of the infections have shown that internal thread
rate limiting seems to be broken in certain situations. Which means that
some infected systems will continue to spawn new threads until system
resources become so low that the entire web server computer crashes or
becomes unusable.

Summary
-------
We will be releasing a full detailed analysis, complete with
disassembled worm code and comments within the code.

We have had reports from a few network administrators that their IDS
systems have seen this .ida attack originating from over 5 thousand
unique source addresses within a 3 day time span.

Hosts early in the IP sequence will be hit with a traffic based denial
of service and those hosts vulnerable to this worm will most likely
grind to a halt.

How to secure your system from this .ida attack
-----------------------------------------------
Microsof patch for this .ida vulnerability
http://www.microsoft.com/technet/treeview/default.asp?url=/technet/secur
ity/
bulletin/MS01-033.asp

eEye Digital Security Advisory
http://www.eeye.com/html/Research/Advisories/AD20010618.html

The following is part of the packet data that is sent for this .ida
"Code Red" worm attack:
/default.ida?NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
NNNN
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
NNNN
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
NNNN
NNNNNNNNN%u9090%u6858%ucbd3%u7801%u9090%u6858%ucbd3%u7801%u9090%u6858%uc
bd3%
u7801%u9090%u9090%u8190%u00c3%u0003%u8b00%u531b%u53ff%u0078%u0000%u00=a
HTTP/1.0

You can set your IDS to monitor for this to be able to see if your being
hit with this worm or not. Also any IDS capable of detecting the .ida
overflow should be able to detect this as an attack.

Signed,
eEye Digital Security
T.949.349.9062
F.949.349.9538
http://eEye.com/Retina - Network Security Scanner http://eEye.com/Iris -
Network Traffic Analyzer http://eEye.com/SecureIIS - Stop known and
unknown IIS vulnerabilities

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