Practical Decryption Exfiltration: Breaking PDF Encryption

Explore the vulnerabilities in PDF encryption through this 35-minute conference talk from WAC 2020. Delve into the Portable Document Format, examining who uses PDF encryption and the attacker model. Gain insights into PDF encryption fundamentals and discover gaps in its security. Learn about various exfiltration techniques, including simple content overlay, direct exfiltration through PDF forms, hyperlinks, and JavaScript. Investigate malleability gadgets, known plaintext attacks, and their impact on PDF signatures. Understand the importance of closing backchannel vulnerabilities and consider short-term mitigation strategies. Conclude with a comprehensive overview of practical decryption exfiltration methods for breaking PDF encryption.