IT Forensics · Courts

Is it possible to determine when a file was created or modified?

Zeitstempel wirken auf den ersten Blick eindeutig. In der Praxis gehören sie zu den am häufigsten missverstandenen digitalen Spuren. Eine Datei kann mehrere Zeitangaben besitzen, deren Bedeutung vom Dateisystem, Betriebssystem, Anwendungsprogramm und Übertragungsweg abhängt.

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Eine kopierte Datei kann beispielsweise ein ursprüngliches Änderungsdatum behalten, während ihr Erstellungszeitpunkt auf dem Zielsystem neu gesetzt wird. Cloud-Synchronisation, ZIP-Archive, Backups, E-Mail-Anhänge oder Dateiwiederherstellung können Zeitangaben zusätzlich verändern.

Deshalb beantworten wir die Frage nach Entstehung oder Veränderung einer Datei nicht anhand einer einzelnen Spalte in einem Forensikprogramm. Wir prüfen die Zeitangaben in ihrem technischen Zusammenhang und suchen nach unabhängigen Spuren, die den behaupteten Ablauf bestätigen oder ihm widersprechen.

The actual question of evidence

Wie wird ein Dateizeitpunkt forensisch abgesichert?

Zunächst wird festgestellt, welche Zeitstempel überhaupt vorliegen und was sie technisch bedeuten. Danach werden Dateisystemdaten mit Dokumentmetadaten, Anwendungsspuren, Backups, Snapshots, E-Mail- oder Cloud-Kontext und gegebenenfalls Protokollen verglichen.

Sind mehrere unabhängige Quellen zeitlich konsistent, kann sich daraus ein belastbarer Zeitraum ergeben. Widersprechen sich die Quellen, wird dieser Widerspruch nicht geglättet, sondern untersucht und im Gutachten erläutert.

Where the limits of what can be said lie

Ein einzelner Zeitstempel beweist regelmäßig weder die Person, die eine Datei verändert hat, noch die konkrete Handlung, die zu diesem Zeitstempel führte.

Why LanCologne?

In the case of court-ordered investigations, it is not a matter of which analysis programme displays a match first. What matters is whether the question of evidence can be answered on a technical basis and whether that answer stands up to independent scrutiny.

We adopt an open-minded approach, document the origin of key findings and examine alternative technical explanations. The actual analysis is always carried out on a forensic copy or a dataset that has been securely preserved as evidence. Originals are not examined directly unless absolutely necessary. Where live procedures are technically necessary, any changes that may result from them are explicitly documented.

Depending on the research question, key findings are verified either using a second method appropriate to the subject matter or directly on the basis of the underlying raw data. The tools used for this purpose depend on the evidence and the research question. The key factors are the suitability, professional recognition and traceability of the method – not a product name.

Our report distinguishes between factual findings, technical assessments and remaining uncertainties. A negative finding is justified just as carefully as a positive one.

How we handle court-ordered assignments

How we work – from the court order to the response

We first check whether the matter falls within our area of expertise, what facts the court is basing its decision on, and whether the content or scope of the assignment is clear. If there is any doubt, the court will seek clarification. This is in accordance with Sections 404a and 407a of the Code of Civil Procedure (ZPO).

Any reasons that might give rise to doubts as to impartiality are examined before the substantive investigation begins and, where appropriate, disclosed to the court.

Devices, data storage media, backups and files provided are identified and documented. The status at the time of the investigation is recorded.

Where technically feasible, a forensic copy or image is created. Hash values and other integrity checks are used to ensure unambiguous identification. The original is retained for future verification.

We determine which evidence would support the alleged event, what contradictory findings are conceivable, and which alternative technical explanations need to be examined.

Only those artefacts which have professional evidential value in relation to the issue in question are examined. Automatic matches are not accepted without verification.

Findings relevant to the decision are – where necessary – cross-checked using a second recognised method, a different technical approach or directly against the raw data.

We explicitly examine what conclusions must not be drawn from the data. We identify missing data, possible deletions, technical limitations, incomplete extracts or contradictory evidence.

The final conclusion is drawn from the documented findings. It is not stated in stronger terms than the data permit.

The main text remains accessible even to those without a background in digital forensics. The technical appendix contains the information required by an independent IT forensic expert to carry out a technical review or prepare a counter-report.

ZPO §§ 403, 404a, 407a, 411; § 286 ZPO. Der Sachverständige liefert die technische Einordnung, die Würdigung verbleibt beim Gericht.

The expert provides the factual basis for the case. The legal assessment and the final evaluation of the evidence remain the responsibility of the court.

Frequently Asked Questions

LanCologne – IT Forensics for the Courts

Do you require an independent technical investigation into a matter of evidence for court proceedings? LanCologne examines digital evidence objectively, transparently and in a reproducible manner. We document both positive findings and the absence of evidence, as well as technical limitations, in such a way that the conclusions remain comprehensible to the court and verifiable by an independent IT forensic expert.

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