Breaking encrypted data using Burp
Summary: PortSwigger added a new Burp Intruder payload type for automatically testing for vulnerable ECB-encrypted data, following an earlier payload type for CBC bit flipping. Because ECB encrypts each block separately, identical plaintext blocks always produce identical ciphertext, so blocks can be duplicated and shuffled to alter the decrypted structure - in the article's example, inserting a copy of the 'app=' block after the 'uid=' block changed the token's user ID from 218 to 992.
What you should know: The attack succeeds only if the application reads the modified field, ignores the duplicated one, and never checks the integrity of the whole token - and in the article's test run, that was enough to land a session as an application administrator.
Read the original at PortSwigger Research ↗
- Topics
- Vulnerabilities & Patching
- Related
- Attackers Exploit UnrealIRCd Flaw That Enables Server-Level Command Injection Cyber Risks · Nov 14, 2026U.S. CISA adds Check Point and UnrealIRCd flaws to its Known Exploited Vulnerabilities catalog Cyber Risks · Nov 14, 2026PostgreSQL Patches 52 Flaws, Including 22-Year-Old Bug Enabling Authenticated RCE Cyber Risks · Nov 13, 2026