A police digital forensics expert has admitted that some mobile phones are impenetrable to software used by police in forensic examinations. The revelation follows a paper by a Cambridge researcher which originally made the claim.
"There are some phones that are not supported by any tools," said Kevin Mansell, a hi-tech crime trainer for Centrex, the police training authority. Among other disciplines, Mansell trains officers in retrieving data from mobile phones.
"But it's important to remember that data on phones can always be retrieved manually, just as you would navigate through your own phone," Mansell told OUT-LAW.
The claim that some models of mobile phone are impenetrable to police forensic searches came from a Cambridge University researcher. Tyler Moore, a PhD student in computer security at Cambridge, analysed the way police forces conduct digital forensics. He found that a lack of phone operating system standards means that forces do not always have the right tool to penetrate a phone.
"Uncommon phone types are often inaccessible with standard software products," he told OUT-LAW. "This is an undesirable outcome for law enforcement, and it is a direct consequence of mobile phone manufacturers' choosing to store data in proprietary formats rather than standard ones."
Retrieving data from mobile phones has become a vital part of police work, Mansell said. "Law enforcement is examining mobile phones every single day. Think how much you use your phone, how long you've had it," he said. "The longer you have it the more it becomes a fingerprint of the way you live your life. That is of interest if you are a suspect, a victim or a witness in a case."
Moore chose to examine the differences between forensics for computers and for mobile phones. Computers store information in standardised formats, making data relatively easy to retrieve. The fact that mobile phone manufacturers write their own operating systems has serious implications for policing, he argues.
"The main point of my paper is to introduce principles from economics to digital forensics," said Moore. "Most law enforcement agencies face very real budget constraints, so they are sensitive to the costs of extracting data from digital devices for forensic examination."
"The cost of extracting data on mobile phones is higher, since software has to be individually developed for each manufacturer and tailored to individual models.
"Some tools work with 200 phones, but when you think that a phone that comes in for examination could come from any manufacturer and be from the last 10 to 15 years, you see that 200 is only a fraction of the total," said Mansell.
The sheer number of phones to be examined in cases poses a challenge for the police. "Volume is an issue, but one that can be dealt with by resourcing and hopefully with new and better forensic tools," said Mansell.
Mansell pointed out that time-consuming manual examination can still retrieve phone data. There does not, though, appear to be an easy solution to retrieving deleted data on a phone for which there is no examination software.
Though mobile phone networks keep some data, it is often not as detailed as the police would like. "Law enforcement would like them to keep everything and forever," said Mansell. "In reality it ends up being a compromise."
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