Carnivore substitute keeps Feds honest

Mitigating on-line terrorist witch hunts

The Forensics Explorers division of CTX has lately come to market with a Carnivore-like suite called NetWitness which, the company says, can enable ISPs to surrender to the Feds only those specific bits of information about a suspect which a court has authorized for collection.

The NetWitness package can separate data to ensure strict, minimal compliance with a pen register or trap and trace order, and later associate the original content if a search warrant or a wiretap warrant is issued, Forensics Explorers General Manager Mark Longworth told The Register.

Because Carnivore is capable of capturing far more data than a pen register or trap and trace order is meant to make available, an ISP may well prefer to install its own kit rather than trust Carnivore operators to stick to the letter of the law.

There are two chief problems with Carnivore in terms of over-collection, as we reported in a previous article. First is the fact that packet traffic belonging to perfectly innocent subscribers passes through it along with the suspect's data. Basically, we have to trust the FBI not to abuse this incidental access. The motive for them not to do so is the looming possibility of screwing up a prosecution; but now, in the wake of the 11 September atrocities, it's a fair bet that the Feds are going to get a good deal more latitude from the courts in borderline cases.

The second problem is that we have no assurance that, when used in 'pen mode', Carnivore doesn't capture more of the packet than its origin, destination and time of transmission. It's quite possible that the subject line of an e-mail memo would be captured, for instance. This certainly goes beyond what's understood as a pen register or trap and trace, where only the origins and destinations of phone calls are to be recorded.

The FBI is now exuberantly installing Carnivore on public networks in pursuit of the Bearded Chupacabra. But it's reasonable that an ISP, however eager to cooperate in this venture, might well object to having a mysterious 'black box' installed on its lines. But the fact is, it doesn't have to, so long as it can provide the FBI with the data it's authorized to collect.

Doing in-house surveillance can become a feature with which an ISP might differentiate itself from its competitors. For example, you the innocent subscriber can be assured that if a pen register is executed against someone else on the network, your e-mail isn't going to end up in the hands of the FBI. And if you're ever unfortunate enough to come under federal scrutiny, you can be assured that the FBI won't be getting any data beyond what's been legally authorized.

There is no logical reason for the FBI to insist that an ISP use its black box. Phone companies don't let them install mysterious devices on their lines, and neither should ISPs. These collections are covered under the CALEA (Communications Assistance to Law Enforcement Act), which obligates communications providers to comply, all right; but that isn't the same as saying that only equipment cobbled together by the Feds can be used.

The FBI's irrational devotion to Carnivore is most likely the result of needing to justify the development costs, which we're told were in the neighborhood of $3 million. Pushing it aggressively is essentially a way of denying that it's a sub-standard tool.

The NetWitness kit is well within the reach of most ISPs; the collector sells for approximately $2,500 and the analysis station for between $35,00 and $45,000, Longworth told us. Network Ice offers a free do-it-yourself Carnivore kit, but this requires development effort. It may or may not end up cheaper than NetWitness, according to the efficiency of one's in-house geeks. ®

Related Stories

How Carnivore works
Network Ice posts do-it-yourself Carnivore kit

Sponsored: 10 ways wire data helps conquer IT complexity