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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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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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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In the footsteps of Bob & Bing

Posted on April 7, 2011. Filed under: forensic, security | Tags: , , , , , , , , , |

Just 2 more days till I’m off to the ISO/IEC SC27 meeting in Singapore and I couldn’t resist the opportunity to use a clip from a relevant film;)

Anyway – some interesting new agenda items have appeared. Of these the most significant is new discussion slot on “Digital Forensic Processes”, suggesting there may be some new work items (aka drafting of new standards). It’s not clear where the request for this has appeared from or exactly what it relates to.

Given that I volunteered to be a rapporteur for study periods on “Digital Evidence Readiness & Analysis” and “Digital Evidence Validation & Verification” it seems a little redundant to me. We (the UK panel dealing with these) are proposing that readiness should be considered as part of Incident Management since it involves planning & auditing, Analysis should probably sit inside the existing draft 27037 document about evidence recovery, since it shares many common features and requirements, and that there should be a new standard for Validation & Verification.

With those in place, we think we cover all the critical phases of an investigation (and we are not going to say “forensic” because we now believe it is appropriate to broaden the standards so that every investigation is carried out to a high standard just in case it needs to go to court) – so I’m curious where the extra discussion has come from. Maybe the committee has realised just how much I like the sound of my own voice ?

 

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Ready or not ?

Posted on March 25, 2011. Filed under: forensic, security | Tags: , , , , , , , , , , , , , |

In a couple of weeks time I’ll be off to Singapore, missing the Malaysian GP (but flying over it), to attend the next ISO/IEC SC27 meeting. Another week of sitting in meeting rooms in an exotic location.

While there, I’ll be proposing some new work that the UK delegation feels is necessary to complement the existing work on ISO 27037 (Identification, acquisition and preservation of digital evidence). Our view is that 27037 represents the middle of a 3-stage sub-process in Information Security Incident handling.

By the time you need to collect potential evidence, and incident has already occurred – and in order to be able to collect useful material you need a plan. Our view is that IS Incident Investigation should start with proper planning, then move on to collection and finally analysis & reporting. All of which should be properly underpinned by a robust validation & verification mechanism.

So – we are going to propose that some new work on IS Incident Investigation Readiness should be conducted, with a view to including it in ISO 27035 (Security Incident Management). Why there rather than in 27037 or a new standard ?

Well – Investigation is just one possible response to an incident – a common and useful one, but not the only one, so it makes sense to have it included in the management standard, which already includes risk assessment & management. Planning needs to come from an understanding of possible incidents and the systems which can be affected. Also, we know that many companies, particularly SMEs, will need to outsource the collection & analysis stages – which is perfectly acceptable – but still need to do their own planning to ensure that the organisation they call in can understand the nature of the incident and the systems affected, and that the methods to be employed in stages 2 & 3 meet the requirements of the plan.

I think it’s necessary work – certainly based on reports I’ve heard over the years from companies who complain that intellectual property breaches and acquisition of commercially sensitive data have not been investigated or prosecuted properly. In every case I’ve considered there has been a failing from day 1 on the part of the company – they didn’t take proper actions to secure the information or data, and they had no mechanism in place to prevent or investigate. As someone once said “Fail to plan and you plan to fail”.

There’s nothing really new in this – Incident Response guides recommend investigation as well as post-incident clean-up as good practice. It helps the organistion to learn from mistakes. The only real difference is that we are planning to set an international minimum standard for it – to help people understand the basic requirements.

If you haven’t already done some planning for incident investigation – why not start now ? or give me call or e-mail ? It needn’t take long, or be hugely expensive – but it could save a fortune if something untoward does happen.

P.S. – note that I haven’t said “forensic” anywhere in this note – not every investigation results in court action – sometimes it just results in improvements internally.

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Contracting

Posted on March 10, 2011. Filed under: forensic, life | Tags: , , , , , , , , , , , |

Just recently I’ve been having discussions about possibly becoming a contractor for a little while and it’s thrown up a question that’s haunted me ever since I started examining other people’s computers.

I’m a fan of open-source software and I really do believe that one of the benefits I offer as a consultant is the fact that I don’t use the same examination kit as everyone else. It means that when I check their results or they check mine we are using significantly different tools, and mine are open for anyone to scrutinise at the source-code level. So, if we find a discrepancy we can dig deep into at least one the tools, if necessary, to find the reason why. It’s proper dual-tooling, or as close as we can get for now.

Now, in the past I’ve had to explain this (because there are two or three tools that everyone expects to see and eyebrows are raised when I don’t mention them ) but it has never stopped me getting an expert witness job. The critical word there is “expert” – in that role I am supposed to exercise my judgment to select the best tools and methods for the job.

However, a contractor is different creature – if I do get offered this job, I have to fit into someone else’s working environment and do things their way with their tools. I can do it. In my academic life I had to learn new skills, tools etc. very quickly and be able to teach them to other people. It’s a knack that a good lecturer picks up soon, or they don’t survive in labs. for long. The question is, will the client believe I can do it or will they wait until they find someone with the right piece of paper instead ?

My argument, for what it’s worth, is that I can learn the tool quickly and, because I have a background in computer science and am used to creating little ad-hoc tools whenever I need them, I can check the tool’s results in a way that someone who just know the program might not be able to.

We shall see.

Meanwhile, in the world of standards and regulation things have gone quiet in the Regulator’s office. His contract has been extended for another 3 years, but I rather think he’s suffering from budget cuts elsewhere. No matter, plans are well underway for the next ISO meeting in Singapore where we will be trying to get some new work approved to go beyond the current ISO/IEC 27037 and ensure we have guidance for a complete process from planning through acquisition to analysis, with proper validation all the way through.

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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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