arXiv subjects

Kaan Onarlioglu

Publications and source records attributed to Kaan Onarlioglu.

3 recordsLinked to original sources

arXiv2026

Web Cache Overflow: Exploiting Imprecise Keys for Cache Degradation and Beyond

Web caches support the scalability needs of contemporary web applications by storing frequently accessed objects closer to clients. Web caches are conceptually associative arrays, tracking stored objects using cache keys consisting of HTTP request fields. However, these cache keys are often imprecisely defined by website operators. This allows clients to craft a multitude of requests that target the same object, but map to different cache keys. In this work, we show that request elements included unnecessarily in cache keys can be abused to create redundant cache entries. In susceptible deployments, sustained generation of such redundant copies reduces cache effectiveness and increases origin load, facilitating eviction-dependent attacks. Our experiments reproduce cache degradation across five stand-alone caching proxies and characterize how these parameters affect attacker cost and cache hit rate, potentially resulting in denial-of-service attacks. We conclude that precise cache-key design is the most direct mitigation against this abuse vector and should be recognized as a security best practice.

cs.CR↗

arXiv2025

HTTP Request Synchronization Defeats Discrepancy Attacks

Contemporary web application architectures involve many layers of proxy services that process traffic. Due to the complexity of HTTP and vendor design decisions, these proxies sometimes process a given request in different ways. Attackers can exploit these processing discrepancies to launch damaging attacks including web cache poisoning and request smuggling. Discrepancy attacks are surging, yet, there exists no systemic defense. In this work, we propose the first comprehensive defense to address this problem, called HTTP Request Synchronization. Our scheme uses standard HTTP extension mechanisms to augment each request with a complete processing history. It propagates this context through the traffic path detailing how each server hop has processed said request. Using this history, every proxy server can validate that their processing is consistent with all previous hops, eliminating discrepancy attacks. We implement our scheme for 5 popular proxy technologies, Apache, NGINX, HAProxy, Varnish, and Cloudflare, demonstrating its practical impact.

cs.CR↗

arXiv2020

Cached and Confused: Web Cache Deception in the Wild

Web cache deception (WCD) is an attack proposed in 2017, where an attacker tricks a caching proxy into erroneously storing private information transmitted over the Internet and subsequently gains unauthorized access to that cached data. Due to the widespread use of web caches and, in particular, the use of massive networks of caching proxies deployed by content distribution network (CDN) providers as a critical component of the Internet, WCD puts a substantial population of Internet users at risk. We present the first large-scale study that quantifies the prevalence of WCD in 340 high-profile sites among the Alexa Top 5K. Our analysis reveals WCD vulnerabilities that leak private user data as well as secret authentication and authorization tokens that can be leveraged by an attacker to mount damaging web application attacks. Furthermore, we explore WCD in a scientific framework as an instance of the path confusion class of attacks, and demonstrate that variations on the path confusion technique used make it possible to exploit sites that are otherwise not impacted by the original attack. Our findings show that many popular sites remain vulnerable two years after the public disclosure of WCD. Our empirical experiments with popular CDN providers underline the fact that web caches are not plug & play technologies. In order to mitigate WCD, site operators must adopt a holistic view of their web infrastructure and carefully configure cache settings appropriate for their applications.

cs.CR↗