String sanitizer modeling

US12182273B2 · kind B2 · utility

Assignee

• SAP SE · DE

Inventors

• Thomas Barber · Schloss Stutensee, DE
• David Klein · New York, US
• Martin Johns · Mansfield, US

Key dates

• Filing date: Feb 4, 2022
• Grant date: Dec 31, 2024
• Expiry date: Jan 13, 2043

Classification

• Technology area (CPC G): Physics
• CPC primary: G06F2221/034
• WIPO field: Computer technology
• WIPO sector: Electrical engineering

Abstract

Code injection is a type of security vulnerability in which an attacker injects client-side scripts modifying the content being delivered. A sanitizer function may provide defense against such attacks by removing certain characters (e.g., characters causing state transitions in HTML). A string sanitizer may be modeled in order to determine its effectiveness by obtaining data flow information indicating string operations that used an input string or information derived therefrom, including a string sanitizer function. A deterministic finite automata representing string values of the output parameter may be generated based on a graph generated from the data flow information, where the automata accepts possible output string values of the sanitizer. It can be determined whether there is a non-empty intersection between the automata for the sanitizer output and an automata representing a security exploit, which would indicate that the sanitizer function is vulnerable to the exploit.