Magic numbers help verify true file types and detect malicious files masquerading as safe formats.
Common signatures
- PDF: %PDF (25 50 44 46).
- PNG: \x89PNG (89 50 4E 47).
- JPEG: \xFF\xD8\xFF (FF D8 FF).
- ZIP: PK (50 4B).
- EXE: MZ (4D 5A).
Security uses
- Detect files with mismatched extensions (.jpg that's really .exe).
- Bypass upload filters that only check file extensions.
- Verify file integrity after download or transfer.
- Identify malware hidden in document files.
Validation
- Check first few bytes against known signatures.
- Compare extension with actual file type.
- Reject uploads with extension/signature mismatches.
Related Articles
View all articlesData Breach Response & Notification Workflow | GDPR & HIPAA
Master the complete data breach response workflow from detection to recovery. This comprehensive guide covers GDPR 72-hour notification, HIPAA breach reporting, forensic investigation, regulatory compliance, and customer notification strategies with practical tools and legal frameworks.
Read article →Understanding PE, ELF, and Mach-O: Executable File Format Deep Dive
A comprehensive guide to the three major executable file formats - PE (Windows), ELF (Linux/Unix), and Mach-O (macOS). Learn their structure, security implications, and analysis techniques for malware research and reverse engineering.
Read article →Why Doesn't Magic Number Detection Work for Plain Text Files?
Understand why CSV, TXT, and other plain text files cannot be identified through magic numbers, and learn alternative methods for validating these common file formats.
Read article →What Are File Magic Numbers and Why Are They Important?
Learn about file magic numbers (file signatures) - unique byte sequences that identify true file formats regardless of extensions, and why they
Read article →