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Viruses: The Code Red Worm

By: Richard Lowe

Article Word Count: 1278 words  [Comments (0)]
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Years from now, we will all look back on the summer of 2001 as


one of the strangest summers in the history of the internet. We


will surely laugh at the frantic gyrations of system


administrators and security professionals because of a worm


called "Code Red". We system administrators will most certainly


chuckle as we fondly reminisce on the late evenings spent


patching server after server at the urging of our security


professionals. And hey, that blue screen or two that resulted


was so much fun to research, and the reinstalls that we had to


do the next day will certainly be the topic of campfire


conversations for years to come! Not!





During late July and early August, Microsoft, CERT (Computer


Emergency Response Team) and the FBI issued emergency bulletins


urging all system administrators to patch their web servers


immediately. The press was alerted and asked to help spread the


word that the internet itself was in extreme danger. Every


security and antivirus company on the planet was busy sending


out notices to everyone they could find that the problem had to


be fixed immediately, or dire consequences would result.





The predictions were that internet speed would be reduced to a


crawl for days while billions (trillions?) of meaningless


packets were thrown at the Whitehouse web site an attempt to


knock it off the air.





What was the cause of this three-ring circus?





It's very simple really. The same old story. Microsoft had a bug


in their web server code. Well, saying they had a bug


dramatically understates the magnitude of the problem.





To put it into perspective, let's say you hired a contractor to


build a new bank (you are the bank manager). Naturally, your


bank is outfitted with state of the art technology (so says the


brochure), including a shiny, well-publicized security system.


The project was expensive, but you're happy because, hey, it's


the new, improved, extra special XP bank. Besides, the


contractor is the biggest one on the planet and, frankly, you


paid them an exorbitant rate to ensure that you got the best


there was.





After your bank is robbed, you find out that the contractor had


"accidentally" left an eight foot hole in the right wall. This


isn't just a small hole, it's a huge, gaping crevice leading


directly to the vault. It's in plain view to everyone, except,


seemingly, the contractor. When you confront the contractor to


ask them how they could do such a stupid thing, they politely


tell you, after a three hour wait on hold and a $295 charge on


your credit card, that it's really your fault because you didn't


follow the instructions in their special security bulletin two


months ago. Didn't you send a couple of your employees to the


BSE (Bank Systems Engineer) classes to learn that they need to


purchase the extra-special, super spectacular BankNet


knowledgebase CDs?





Okay, all kidding and sarcasm aside, there is a bug in the


Indexing service (the component that creates searchable indexes)


in the Microsoft Internet Information Server (the program which


displays web pages on a web server) which is supplied with


Windows NT and Windows 2000. This bug allows allows anyone who


can send a special string of characters to a web server to "take


control" and, basically, cause the web server to do anything


that the attacker desires.





The bug is something commonly known as a "buffer overflow",


which simply means you can send more characters to the web


server than it is capable of receiving. When a program receives


characters it writes them to memory in a place called a buffer.


If a poorly written program receives more characters than it is


designed to handle, it will, under special conditions, cause the


extra characters to be executed with privileges.





To put it very simply, it was discovered that you could cause


the Indexing Service to "overflow it's buffers" and execute


selected code as a privileged user. This allows a special hacker


program (which is reported to have required all of a half hour


to write) to gain control of a server.





You have to understand that buffer overflows are nothing new to


the world of computing. In fact, I am sure that the first


programmer is also the first person to experience this


condition. This is well known to competent quality control


departments, programmers, designers and, of course, hackers.





To put it bluntly, buffer overflows should not occur in any


program written by any programmer who has passed "programming


102". In addition, any quality assurance person who has taken


"quality control 101" should be able to check for and spot the


problem from a mile away. All right already, so what is the


infamous Code Red worm?





Code Red is a clever little program which takes advantage of


this gaping hole in the Index Server. What the program does is


search for systems with the flaw. It's easy to find those


systems and Code Red is very good at it's job. So good, in fact,


that in early August 2001 it is estimated that it infected over


300,000 machines!





Once the worm finds a machine, it executes the buffer overflow


condition and causes itself to be installed on the machine.


Remember the Wrath of Kahn movie where the beetle with the big


pincers crawled into Checkov's ear? It's something like that.





Once the bug got into his brain, oh sorry ... once the worm has


installed itself it does a number of different things depending


upon the day of the month. Some days near the beginning of a


month it will search for new systems to infect. Towards the


middle the worms will all launch an attack against the


Whitehouse web site. At the end of the month, all of these


malicious little programs will sleep, waiting for the next month.





Interestingly, the Code Red worm has a couple of small flaws.


First, it's attack is directed at a single IP address. Thus,


during the first waves of attacks in July the Whitehouse "dodged


the bullet" by simply changing their address.





Second, the worm only installs itself in memory. This means it's


simply a matter of rebooting the server to rid it of the pesky


infection. Of course, if you don't install the patch (a fix to


repair the problem, conceptually like the piece of rubber used


to patch a hole in a tire), it's just a matter of time until


your system gets infected again.





Naturally, a new worm called "Code Red II" worm has been


reported in the wild, and almost certainly does not include


these flaws. Hopefully system administrators will comply and


install their patches so their systems will not be assimilated


into the Code Red and Code Red II attacks.








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