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

By Robert Lemos
SecurityFocus
23rd October 2006

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


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