Original URL: http://www.theregister.co.uk/2006/10/23/linguist_fingers_security_troll/

Researcher attempts to shed light on security troll

It's all in the writing style

By Robert Lemos

Posted in Security, 23rd October 2006 09:12 GMT

For over a year, subscribers to the Full Disclosure security mailing list had to endure the taunts and rants of a self-styled vulnerability researcher known as "n3td3v."

The troll - as such taunting posters are dubbed - would frequently ignite massive angry email responses, or flame wars, at times limiting the usefulness of the Full Disclosure list. Over time, n3td3v took on multiple online personalities, or gained members of the n3td3v group, and attempted to create an online security hub. The group's favorite targets included Yahoo!, Google, other researchers and security news reporters, including this one.

Even after n3td3v gave up the virtual ghost in September 2006, no one knew the name of the person who infuriated, and amused, so many researchers. Now, an independent security consultant believes that linguistic forensics - a branch of science that attempts to identify authors by the content and style of their writings - has linked n3td3v with a previous security-list troll and hacking group known as Gobbles.

In a 19 page report published on Friday, consultant Neal Krawetz argues that statistical analysis of mailing-list messages posted by n3td3v and advisories written by Gobbles indicates that each group appears to be three, or possibly four, people, and the writing styles of the people making up the two groups appear to match. The report uses five different metrics of writing style to determine whether the authors are American or non-American, male or female, and their degree of education. While the five indicators have large margins of error, using the methods together minimises the error, Krawetz claimed.

"Because these methods are not perfect, I definitely could be wrong - I just don't think I am," Krawetz said in an interview with SecurityFocus.

The conclusion is not new: Several security researchers that subscribe to the Full-Disclosure mailing list have also noted that n3td3v's tactics seemed similar to Gobbles. However, this is the first time that science seemingly backs up the conclusion.

Krawetz argued that the link could mean that n3td3v's claims of having zero-day vulnerabilities in Microsoft, Yahoo! and Google software could have some basis in reality. In 2001, Gobbles taunted the community, was written off as a troll, but then surprised many researchers by releasing a number of respectable vulnerabilities in late 2001 and 2002.

"Assuming that they are the same group and they are following the same pattern, then (n3td3v) are probably sitting on a lot of zero-day exploits and, probably, for Windows Vista," Krawetz said, stressing that the hypothesis was only conjecture.

Yet, others believe that any link between the two groups is purely circumstantial.

"Gobbles showed some real techniques; n3td3v is nothing but a troll," said Brian Martin, a network security consultant, who asked that his company name not be mentioned. "If you sit down and really think about trolls, Gobbles is going to come to mind. But for no other reason than he's a notable troll."

Martin has met the primary researcher - who used the pseudonym "Gobbles" - in the past and characterised the person, who he refused to name, as "polite and soft-spoken". He doubted that the person who primarily used the Gobbles nom de plume would devolve into more prolific troll.

"Several years later, I don't see him turning into n3td3v at all," Martin said. "Sure he was a troll, but several years later, I don't see him getting worse."

Moreover, Krawetz's forensics analysis does not stand up well, said Carole Chaski, a forensic linguist and principal researcher at the Institute for Linguistic Evidence, Inc. Chaski makes a living out of researching ways of identifying authors and has analysed suicide notes and threatening email in criminal cases to determine authorship.

She stressed that techniques such as measuring vocabulary, spelling errors and grammar errors are not good methods of identifying a document's author.

"This whitepaper floats some of these erroneous ideas which have already been shown by research, which the whitepaper is apparently unaware of, to be fairly unreliable for authorship analysis," Chaski said in an email interview.

Chaski also took to task the paper's assertion that, if the errors in the methods were consistent in either being right or wrong, then the accuracy of the identification is improved.

"There is an old expression 'two wrongs do not make a right' which applies here," Chaski said. "If one method is only 60 per cent accurate and it is combined with another method - for the nonce let us assume an independent method - which is only 60 per cent accurate, than the combined method has an accuracy rate of 36 per cent, far below chance. One would be better off guessing than combining unreliable methods."

Security consultant Krawetz started researching the identity of n3td3v after another Full Disclosure subscriber challenged him to use linguistic forensics - a topic on which Krawetz presented at this year's Black Hat Security Briefings - to uncover the person's identity. He started with the hypothesis that n3td3v and Gobbles were the same and used methods of gender determination as well as analysing lexicon, word frequency, punctuation frequency and preferred sentence length to create a profile of the two groups.

The analysis seemed to indicate that n3td3v had three members and Gobbles had three or four main members. The characteristics of three members of each group seemed to match up.

Krawetz acknowledges that some aspects of his analysis could have significant error. For example, this is the first time that he attempted to analyse documents to match up three different authors, a research problem that ILE's Chaski believes to be untenable.

Krawetz hopes that, if his analysis is shown to be in error, it will ultimately benefit his research.

"Very few people are using these techniques just because they are new technologies," he said. "On the other hand, if someone comes out and shows me I'm wrong, it could help me tune my system."

This article originally appeared in Security Focus.

Copyright © 2006, SecurityFocus