A difficult decision.

Posted on October 29, 2015. Filed under: Uncategorized | Tags: , , , , |

I’ve just decided not to renew my membership of a particular “professional” body. There are many reasons behind this, but the main one is that I’m tired of hearing that they “don’t understand digital”.

I really can’t say any more without ranting, so let’s leave it at that.

This decision may have a knock-on effect on the membership of various committee where I’ve been representing that organisation, in spite of (what I consider to be) a lack of support. We shall have to wait and see.

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Getting the right question

Posted on April 22, 2015. Filed under: business, forensic | Tags: , , , |

One of the biggest challenges for anyone who offers a consulting service is getting the client to ask the right question. All too often, the client already has an idea of what they think the answer is and produces a question around that answer.

An example:

On a forum that I frequent, one of the members asked about where to get a PDF editing program. Lots of people threw suggestions at him, some free, some very expensive, some somewhere in the middle and all were dismissed as too complicated for what the asker needed. So I asked a simple question – “What are you actually trying to achieve ?”.

It turned out that his company had a temporary problem – the document feeder on their scanner wasn’t working properly and they were getting blank pages in between the scanned pages because they had to feed them in manually. He didn’t really need a PDF editor, all he needed was a way to get rid of the blank pages. I suggested that what he should do was load up the files produced by the scanner and then re-print them to PDF, setting the output options to skip every second page. Job done. Free, easy and using a system he already understood and had readily available.

The same thing happens in forensic science, especially in the digital forensic world. People make assumptions about the evidence they need or think they can get, instead of describing the problem they are trying to solve – defining the investigative requirement. The crucial skill for the forensic scientist is not in the realm of technical solutions, but in old-fashioned requirements elicitation.

That’s why I have a rule that I won’t start work until I’ve had a proper discussion with the client and got the answers to “What are you trying to achieve?” or “What problem are you really trying to solve?”.

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Research, funding and reputation

Posted on March 20, 2014. Filed under: Education, forensic | Tags: , , , , , |

I had an interesting conversation, last night, with some fascinating figures from the world of forensic science. Since the whole event was under Chatham House rules, I’m not going to disclose who was present or even what most of our discussion was about, but there was one thing we touched on where I have a fundamental disagreement with at least one senior figure. That area is academic research in forensic science.

The view taken is that the problem lies in funding – in order to stimulate forensic science research, money needs to be available. Well, great – yes, that can help and I’m delighted that FoSciSIG is looking at this. I was certainly lucky enough, during my academic career, to be awarded some EPSRC funding for a project on Cyberprofiling, and I think we did achieve something, but we had a bigger problem. We really struggled to get our results published and to be taken seriously.

Our problem was that, at that time, there was no well-recognised journal for digital forensics, so we had to either target more mainstream computing & info. sec. journals, or go for more general forensic science. In the case of the former, we had problems because our research was very much applied research and hence didn’t have quite the level of generality and “blue sky” content that was expected, and for the latter, we were up against reviewers who were more familiar with “conventional” biology, chemistry and physics type forensic science. In either case, we had to consider the “reputation” value of where we were going to publish too. It’s been a common problem for forensic science researchers for years and it has a nasty knock-on effect.

In order to get published, you often have to seek out a journal for the scientific area, rather than the forensic, and modify your writing to suit that journal. Pressure is often brought to bear to get your work in something with a high “impact” rating rather than the most appropriate channel for dissemination. As a result, your work can be categorised under the more general science, and the forensic nature is often missed. When research managers look at your output, you are no longer a forensic scientist, so the department doesn’t see any benefit in supporting forensic science and that message spreads. Don’t believe me ? Look at the Research Assessments.

The net effect is that, contrary to what senior academics might say, forensic science can be seen as something which is a spin-off from other research, something of an accidental side-effect which just happens because of good science, not something that deserves to be a discipline in its own right influenced by the needs of investigators and courts, so departmental management don’t encourage it, and without their backing there’s no call for funding bodies to take it more seriously.

Out in the practitioner world, one message we all receive very quickly is that the forensic sciences cannot stand on their own – we have to work in teams, with results from different sciences being integrated and influencing the investigative strategy. Heck, that’s even a fundamental message in most degree programmes now.

I was lucky enough to be a computer scientist in a department full of biologists, chemists, physicists and crime scene specialists once. I learnt a hell of a lot from and it changed my approach to digital investigations. If we could just achieve something similar in the research world, we might do something really significant.

As always, I’d love to hear your thoughts. Please do share them in the comments.

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Dear Sir/Madam – I’m looking for a placement

Posted on March 28, 2013. Filed under: Education | Tags: , , , , , |

Dear student

Thankyou for your email. Unfortunately we are not in a position to offer placements at the moment, but may be able to offer some advice which will help you secure one with one of the larger firms (assuming you read past this paragraph).

Firstly, when sending emails such as this, it is a good idea to use your official University email address. Hotmail/Yahoo/Googlemail looks unprofessional and regularly diverts straight to the spam bin.

Secondly, try finding out who you are writing to and direct your email to them in person. My details are not hard to find on our website, but you used our general enquiry address. Again, this looks unprofessional and suggests you are mailbombing rather than being selective in your applications.

Thirdly, you’ve told me what you want – but how can you help me ? or anyone else you contact ? What can you add to the organisation ? Why do we need you ? How much do you know about us ? (give me a clue that you’ve done some research and particularly want to work for me, not just any old firm).

Fourthly, tell the person reading your email something about the course, what your interests are and what your prospects are. At the moment, all I see is that you have to do a placement, not that you *want* a placement.

Finally, rather than making me open your CV, tell the reader a bit more about yourself – make them want to read your CV. Remember you have just as long as it takes for someone to hit “delete” to make a good impression. Most of us receive several of these a week – you need to stand out. You haven’t even told me which University you are studying at so I can’t evaluate you without opening an attachment which might contain malware.

I wish you well in your search for a placement, and hope you will accept these suggestions in the spirit in which they are offered.

Angus Marshall, CEO and ex-academic (who used to find placements for his own students rather than making them do it themselves).

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Time to think

Posted on March 29, 2012. Filed under: forensic | Tags: , , , , , , |

I’ve just spent the day at the RSA running a workshop as part of a project I’m engaged on for a major client. The theme was, unsurprisingly, based around digital forensic standards, processes and scenarios.

Lots of good stuff came out of it and there’s been a huge amount of support, but the disappointing thing was the response from just one organisation. Asked to participate in the project by coming to a one-day workshop and letting me visit them to observe their methods, they responded  (paraphrased)  :  “No. Too disruptive, no time, we have too much of a backlog”.

It seems to me that if you spend all your time trying to use your current methods to reduce a backlog of work, and failing, perhaps a bit of disruption and time off might pay dividends in the longer term.

What are your thoughts ?

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Excellent news

Posted on November 29, 2011. Filed under: All, Education, forensic | Tags: , , , , , , , , , , , , |

Yet again, other activities have kept me away from this blog for far too long. Personally, I think that’s probably a good thing. A mix of casework and research commissions means I can afford to eat properly again (and those who know me will know how important it is that I maintain my physique – particularly in the current high winds).

The major projects that are keeping me busy are on a new website : Forensic Excellence where work on two of the three major elements of “forensic” quality systems is underway. The other bit of news is that I have an interview for funding of some work on the third element, and hope to be able to kick that work off towards the middle of next year.

Onwards and sideways!

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Nothing else of significance…

Posted on July 31, 2011. Filed under: forensic | Tags: , , , , , , , |

This week I was approached to quote for a defence case. Helpfully, the solicitor sent me a copy of the prosecution statement so I could prepare a realistic quote. Unfortunately, for the “other side”, I’ve spent most of the week working on a couple of proposals for new ISO standards – including something on content of reports for various purposes – so was particularly sensitive to languages issues.

As soon as I saw the source of the statement, I knew I was going to find a phrase that troubles me – and there it was, near the end “Nothing else of significance was found”.

The report details the material upon which the case is based, but gives little in the way of context or other material found. It builds the case for the prosecution solicitor nicely, but doesn’t allow anyone else to form an opinion about the significance of the material because it doesn’t actually give any detail of anything except the “significant” material as determined by the report’s writer.

It’s a format and form of words that I’ve seen several times over the years, and every time I see it, it sounds an alarm.

I’ve always been told that my responsibility as an “expert witness” is to the court (or whoever is going to make a final judgment based on all the reports submitted), and is to state the facts and my interpretation as best I can based on the information available to me. If I find evidence of guilt, I should state it, if I find evidence of innocence, I should state that. I also believe that I should try to make as much information as possible available so that a proper judgment can be made.

To this end, I don’t just list things of “significance” but I try to give an indication of the context in terms which a non-practitioner can understand.

For example, if an email relates directly to the case, I don’t just list that email. I give the total number of emails found and the number found which involve the same people in the “significant” one. If illegal images are found, I try to determine how they have been downloaded, whether they’ve been deliberately saved or just cached, and whether there’s a pattern of searching or browsing that relates to them.

I try never to build a case directly myself but I will, quite happily, poke holes in someone else’s case – especially if they are concealing, deliberately or accidentally, useful information behind statements like “nothing else of significance was found”.

In my book, saying something like that is almost tantamount to dissembling. A digital evidence examiner rarely has the full facts and circumstances of the case available. A prosecution examiner or first responder will have no idea of possible defences or excuses. Limiting the report to the most damning evidence doesn’t help anyone.

Well – it doesn’t help anyone except the “other side”. A good independent examiner will read that sort of report and realise that there’s a lot more work they could do, and SHOULD do, to determine if a proper rebuttal can be produced – and that means more time and bigger fees. I’m not a fan of the use of Bayesian ratios in reports because I know how few people really understand them, but I know why some forensic disciplines use them – they force the reporting scientist to think about the evidence and alternative explanations, resulting in a closer examination of “insignificant” material at times.

At a time when pressure is on to reduce spending on legal aid, perhaps it’s time someone looked more closely at standard reports coming from both sides to see if they are really fit for purpose ? The better those reports are, the less work needs to be done performing re-examination, re-analysis and re-interpretation.

n-gate ltd.

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Valid conclusions?

Posted on July 12, 2011. Filed under: forensic | Tags: , , , , , , , |

WARNING : Initial thoughts on a recent situation ahead – incomplete  – more to follow, eventually !

Recently, the Casey Anthony trial in the USA has been a source of discussion in many fora, but most recently a bit of a “spat” seems to be in danger of breaking out between the developers of two of the tools used to analyse the web history.

Leaving aside the case itself, let’s start by looking at what the two developers have to say about the issue that came up during cross-examination :

http://blog.digital-detective.co.uk/2011/07/digital-evidence-discrepancies-casey.html

http://www.cacheback.ca/news/news_release-20110711-1.asp

No preference is implied by the ordering of those links, by the way, it’s just the order in which I became aware of them. I don’t use either tool – I have my own methods for doing these things when necessary.

Two issues arise from these two posts, for me :

i) Both developers admit that there were possible problems with their tools which may have resulted in incorrect results and no-one was aware of this until the two tools were run side by side

ii) Neither tool seems to have been validated for the case in question. I’m sure they were verified (i.e checked for conformance to design/specification) but not convinced that they were tested against the requirements for the case.

Here comes the repetitive bit : as far as I’m concerned under the requirements of current and proposed ISO standards, neither tool could be considered reliable. There is no clear documentation about errors nor is there evidence that either has been subjected to a proper structured validation process. Dual-tooling is not validation. It merely compares two implementations of methods designed to solve the same problem as the developers understand things. At no point does anyone check that the results are correct, just how similar they are. Two implementations of the same wrong algorithm are more likely than not to come up with the same wrong results.

This is typical of the issues we will see more and more of in the digital forensics world – we depend too much on third-party tools which use algorithms developed through reverse engineering and have not been completely tested.

I’m not suggesting that every tool needs to be tested in every possible configuration on every possible evidence source -that’s plainly impossible – but we do need to get to a position where properly structured validation is carried out, and records which document that validation – including areas which have NOT been tested – are maintained and made available.

An examiner should always be free to use new methods, tools & processes, but should be personally responsible for choosing them and justifying their use. Information about usage limits & limitations on testing are vital and any competent examiner should be able to carry out additional validation where it is needed.

Let the flamng (of this post) begin…

 

P.S. – I’ve been doing a lot of work on models & systems for validation recently – they’re currently commercially confidential but if you’ld like to discuss the issues more please do contact me via n-gate.net

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It’s the little things

Posted on June 8, 2011. Filed under: forensic | Tags: , , , |

A while back I was asked to help out with a fraud case. The investigators had done a pretty decent job of extracting relevant information but a critical aspect of the hinged on the dates when a couple of letters were written. We had some issues around the way a disc image had been captured which meant that everything except the “last modified” date was considered unreliable.

These letters had been written in word and the timestamps in the filesystem were about 2 years AFTER the dates in the text in the documents. The meta-data in the documents agreed with the filesystems.

The defence experts, quite rightly, put forward a suggestion that the computer used to create the documents could have had an inaccurate clock, possible even set to a future date. Unlikely, in my opinion, but possible and probably enough to create “reasonable doubt” if the evidence came to court.

However, as we explored the issue further and got further and further into the niceties of Windows XP clock synchronisation using NTP when connected to the Internet something in my subconscious prodded me.

Just out of curiosity, I ran the GNU “strings” program against one of the documents and out popped a couple of JPEG JFIF headers. so – I carved out the two JPEGs and checked the EXIF data. Both contained dates which matched the filesystem – hardly surprising and not much help countering the “clock was wrong” argument – but they also contained a signature from the program used to produce them. It was a version of photoshop which wasn’t produced until at least 18 months after the dates in the letter text.

Either the suspect had been indulging in time travel, or the letters as printed must have been created some time after the date he claimed.

Sometimes, we forget that there’s more to timeline analysis than just the clock data. Knowing when a piece of software or a file first appeared can be very helpful too.

http://www.n-gate.net/

 

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ISO ISO baby – part 2

Posted on April 20, 2011. Filed under: forensic, security | Tags: , , , , , , , , , , , |

Well, I’m just about back on BST after spending last week in Singapore. In the words of Robin Williams – “IT’S HOT!” out there, and sticky, but the locals are very friendly, the food is excellent (Kopi & Kaya Toast highly recommended for breakfast).

Of course, I wasn’t just out there for a “jolly” (but thanks for dinner Microsoft – I promise to say nice things about you for a few hours at least), but was attending the latest meeting of ISO/IEC JTC1 SC27 working groups. This is the “Information Technology – Security Techniques” sub-committee responsible for the infamous 270xx family of standards.

My main responsibility was to assist with the ongoing task of editing the 27037 “Guidelines for the identification, collection, acquisition and preservation of digital evidence” document. It’s coming along nicely, but we still have considerable debate about whether this is a standard for law-enforcement, Infosec. or both.

My own view is that, because of the nature of the committee responsible, it needs to be an Infosec. document which can be useful for everyone – including law enforcement. This approach to it seems to be paying off as some of the resistance to it is falling away.

The problem with treating it as a document for law-enforcement is that any international standard in this area is bound to come into conflict with local law, local procedure etc. (you’ll see the truth of that when you read the final version and see how often we have had to include a reminder about local legislation  etc. overriding the guidance). Worse still is the possibility that an ISO document might try to tell judges how to deal with evidence & matters of law.

We can do no more than issue some helpful information and try to set a minimum standard which will allow anyone involved in investigating digital incidents to have confidence that any organisation, working to the same standard, will use methods which are compatible. In that respect, ISO/IEC 27037 looks like it’s going to work. Ideally, of course, everyone will adopt is as a minimum standard – and that can only be good news, because there will better understanding of the issues surrounding digital evidence handling and fewer situations where examiners, like me, have to turn down cases because of problems in the early stages.

I just hope we can achieve the same with the three new projects that we’re hoping to launch in October – “Investigation Principles & Process”, “Guidelines for Analysis & Interpretation of Digital Evidence”, and “Guidance on assuring suitability and adequacy of investigation methods”.  We (the UK group) are also hopeful that our proposal for some new work on “Incident Readiness” (particularly investigate readiness) will also be launched in October.

If you have any suggestions for what should be included in those standards, please do let me know. These things are just written by “the great and the good” (proof : they let me play!) but are the result of debate, discussion and consensus. More ideas  = better results.

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    This is the weblog of Angus M. Marshall, forensic scientist, author of Digital Forensics : digital evidence in criminal investigations and MD at n-gate ltd.

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