Hexadecimal analysis
Inspect bytes directly to understand formats and verify tool interpretations.
The idea
Hexadecimal notation represents bytes in a compact base-sixteen form. A hex editor can reveal file signatures, headers, offsets, and raw content. Analysis should be done on a controlled copy because editing tools can also alter evidence. File-format knowledge helps distinguish meaningful structure from coincidental strings. Use direct inspection to validate a tool’s interpretation, while recognizing that readable fragments alone rarely establish a full history.
In practice
An investigator checks the header of a copied file to see whether its internal format matches its extension and a tool’s classification.
A common misunderstanding
Changing an extension does not change the underlying file type, and a recognizable string is not always a complete record.
Check your understanding
Why record offsets for relevant bytes?
Think it through: They make the observation reproducible within the identified evidence file.
Bytes are evidence; interpretations are hypotheses
Hexadecimal notation represents byte values in a compact form. A hex viewer often shows offsets, byte values, and a text rendering side by side. The text column depends on an encoding assumption, so unreadable characters do not necessarily indicate encryption or malicious content. The same bytes may represent numbers, instructions, compressed data, or text in another encoding.
File signatures and internal structures can help identify content, but a signature alone is not a complete format validation. A file may be truncated, embedded inside another object, or deliberately constructed to confuse parsers. Compare the bytes with documented format expectations and the behavior of appropriate tools.
A fictional mislabeled attachment
An academy receives a training attachment whose extension suggests an image. A hex inspection reveals a different header pattern. The analyst records the relevant offsets and compares the structure with a trusted format reference. The mismatch justifies further examination, but it does not by itself establish the author's intent or whether the file executed.
Work on a copy when changing or experimenting with bytes. An editor can alter evidence, and saving a file accidentally may change content or metadata. Record whether a tool was used only for viewing and retain the original file identity. Hex analysis is particularly useful for checking a parser's claim against the underlying data.
Read a small known file
Create a harmless text file containing a few characters and a line break. Open it in an approved hex viewer and identify the byte offsets and encoding. Compare versions saved with different encodings if your environment supports them. Explain why the displayed text and byte count differ. This builds a concrete understanding before attempting to interpret complex binary artifacts.
Keep exploring
References & further reading
Original explanations, with primary references for deeper study.
NIST: Integrating Forensic Techniques into Incident Response