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SCO's "DDoS Attack" - Was It or Wasn't It?

Why didn't SCO's Linux block all "SYN flood" attacks, ask experts.

Both The Age and The Sydney Morning Herald, two of the biggest news sites in Australia, have already begun asking questions about yesterday's outage at the SCO Web site, which SCO Group described in a statement as "a large scale distributed denial of service (DDoS) attack."

In a piece bylined Sam Varghese and dated today December 11, The Age reports:

SCO said it was working with its ISP to restore service and that the site was unavailable due to a SYN flood attack.

IT professionals have, however, cast doubt on SCO's claims as the operating system on which its website is hosted, Linux, has the ability to block all SYN attacks.

Additionally, it has been pointed out that Cisco, the router manufacturer, has patches in place for its hardware to prevent such attacks. If SCO is facing such an attack then it appears that elementary precautions have not been taken, the pros say.

Web stats provider Netcraft has a graph of the activity before and during the period when SCO says its site was being DDoSed.  

The incident affected SCO's Web site, e-mail, intranet and customer support operations and SCO said that the particular DDoS used is known as a syn attack and used "several thousand servers [that] were compromised by an unknown person to overload SCO's Web site with illegitimate Web site requests."

Steve McInerney, an Australian security expert consulted by Groklaw, however, raises questions.

McInerney, who worked for six years as the Technical Security member of the IT Security team for Australia's Department of Defense and more recently was one of the senior designers/firewall/security experts at a company that manages Australia's largest federal government-certified Internet gateway, is of the opinion that "SCO are NOT suffering a DDoS attack. Specifically not one that they have described. It looks to me like someone has accidentally kicked a cable out of it's socket or similar. Or a HDD failure or...."

"Speaking as a Sysadmin/Firewall guy," McInerney says, "my first priority in any attack is to solve the problem - not issue a press release."

Such debating points aside, here is McInerney's technical rationale, verbatim:

A 'SYN Flood' attack is an attack that attempts to stop a server from accepting new connections. It's quite an old attack now, and has been relegated to the 'That was interesting' basket of attacks. A very simple analogy of a SYN attack: You have two hands, you are thus able to shake hands with at most two people at any one time. A third person who wants to shake your hand has to wait. Either you or one of the first two people can stop shaking hands so as to be able to accept the third person's handshake.

In this instance SCO are claiming that 'thousands' are doing something similar to their web server. This is, in and of itself, plausible. Unfortunately if we look closer there are a few problems with this claim of SCO's.

As stated above, the attack is quite an old one. Patches to all Operating Systems that I'm aware of, do exist to stop this sort of attack. For instance, a CISCO document describes the attack and provides ways to stop it. Note the lines: 'Employ vendor software patches to detect and circumvent the problem (if available).' This means, quite simply, that patches exist to mitigate this attack. Why hasn't SCO applied them?

Further SCO States: "'The flood of traffic by these illegitimate requests caused the company's ISP's Internet bandwidth to be consumed so the Web site was inaccessible to any other legitimate Web user.'

Interesting. If their bandwidth is consumed, then any servers nearby will also be inaccessible. That is www.sco.com has the IP address of 216.250.128.12 and ftp.sco.com has the IP address of 216.250.128.13 so the two servers are side by side, probably even on the same physical network hub/switch. Note that there is no room for a broadcast, etc., address - these servers are on the same subnet - i.e., on the same network device (hub/switch).

Unfortunately for SCO, from Australia, ftp.sco.com is highly responsive. No bandwidth problems there that I can see - even though www.sco.com is still unavailable. The evidence then, is that their bandwidth is fine.

So what about just the SYN flood? Well, even with patches, to successfully conduct a SYN flood you would tend to chew up available bandwidth anyway, which we aren't seeing. So I have quite strong doubts about the accuracy of this information. I feel quite comfortable in stating that SCO are NOT suffering a DDoS attack. Specifically not one that they have described. It looks to me like someone has accidentally kicked a cable out of it's socket or similar. Or a HDD failure or....

Dealing with an DDoS atack when your bandwidth is NOT eaten up is fairly simple. A quick and dirty script to read your firewall log(s) for incoming addresses that are trying the SYN attacks is fairly easy. Adding those IP addresses to a quick block list is also easy.

After this, and other, opinions, the counter-allegation that SCO was perhaps "faking DOS attacks to make Linux community look bad" is now doing the rounds of the Internet. LinuxWorld will endeavor to keep you abreast of whatever consensus on the facts is eventually reached.

More Stories By Linux News Desk

SYS-CON's Linux News Desk gathers stories, analysis, and information from around the Linux world and synthesizes them into an easy to digest format for IT/IS managers and other business decision-makers.

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Most Recent Comments
rusty carruth 12/11/03 03:23:54 PM EST

Note that, before groklaw went unavailable, it appears that
SCO had a non-trivial set of changes to their web pages,
that appear to NOT be caused by a restore of older stuff.

Unfortunately I've lost the url for the site that keeps backups of web pages...

rc

Alexander C. Zorach 12/11/03 10:56:22 AM EST

As a consultant who has set up numerous networks, this is absurd. Nowadays, even the cheap hardware you use can buy at the local store has the necessary capacity to deal with a DDoS attack. If this really was a DDoS attack, I think the http://www.sco.com/ site would be up already. I can't imagine it taking more than an HOUR to fix things, maybe a little more if you have to download some patches or recompile into your kernel the support for blocking the attack.

The fact that it's taken so long either means that there was no DDos Attack, or that if there was, SCO was totally clueless at dealing with something that any small-time computer consultant such as me would have put an end to in a matter of minutes.

John Hinton 12/11/03 09:46:49 AM EST

Please see the commentary (and comments) on www.groklaw.net, which began checking out the "attack" from 11:19 AM EST on 10 December. An ace site with a wealth of shared expertise.

ByteEnable 12/11/03 09:18:59 AM EST

Good story coverage. By the way, I called SCO and asked specifically which Law Enforcement agenices have been contacted and are working the case. I have yet to recieve a response. The FBI should have a Special Agent in Charge assigned to the case.

Josh McCormick 12/11/03 08:52:22 AM EST

Take SCO's claim at their word. They're incompetent. An OS manufacturer and distributor, as well as a web solutions provider, completely helpless against an ancient form of attack against web sites. How can anyone sleep at night, running SCO products, saying, "this company stands behind me"?

The only other credible alternative is that their executives are lying. Can anyone sleep at night knowing that liars are standing behind them?

Either you've got a company that is incompetent in its core competency, or you've got executives who are liars. Either way, this isn't a positive event for SCO.

jar jar 12/11/03 07:51:02 AM EST

SCO wouldn't know a DDOS attack was happening even if it bit them on the arse. Not enough people would visit their web site for them to be alerted that they had a problem. They can't even show they have the technical prowess to "find" stolen code in freely available source code. I visisted their employment section of sco.com. I find it rather amusing that the current UNIX company had some jobs that required the potential employee to know how to use MS Office. No mention of Star Office, Abiword, or any other office productivity software that runs on any flavor of UNIX. I would show specific details, but I doubt Darl turned the web server back on...