CVE-2020-4828 in API Connect
Summary
by MITRE
IBM API Connect 10.0.0.0 through 10.0.1.0 and 2018.4.1.0 through 2018.4.1.13 is vulnerable to web cache poisoning, caused by improper input validation by modifying HTTP request headers. IBM X-Force ID: 189842.
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Analysis
by VulDB Data Team • 02/23/2021
IBM API Connect versions 10.0.0.0 through 10.0.1.0 and 2018.4.1.0 through 2018.4.1.13 contain a web cache poisoning vulnerability that stems from inadequate input validation mechanisms within the HTTP request header processing. This vulnerability allows attackers to manipulate cache behavior by crafting malicious HTTP headers that bypass normal validation checks, potentially enabling them to inject malicious content into cached responses that will be served to other users. The flaw specifically manifests when the system fails to properly sanitize or validate user-supplied input within HTTP headers before using this data to construct cache keys or determine cache behavior.
The technical implementation of this vulnerability involves the application's insufficient validation of HTTP request headers, particularly those that influence caching mechanisms such as cache-control directives, vary headers, or custom headers that may be processed by the API gateway. When these headers contain unexpected or malformed values, the system does not properly validate the input before using it to determine how responses should be cached or served. This creates an opportunity for attackers to inject cache-poisoning payloads that can cause legitimate requests to return malicious content or manipulate the caching behavior of the system. The vulnerability operates at the HTTP layer and affects the application's ability to maintain secure and predictable caching behavior across different request scenarios.
The operational impact of this vulnerability extends beyond simple cache manipulation as it can enable attackers to perform more sophisticated attacks including cross-site scripting attacks, session hijacking, or content injection attacks. When an attacker successfully poisons the cache with malicious content, subsequent users who make similar requests may receive compromised responses that can lead to unauthorized access to sensitive data or system compromise. The vulnerability is particularly concerning in API gateway environments where the system serves as a central point for handling multiple client requests and where caching is frequently employed to improve performance. The potential for widespread impact exists because cached responses may be served to numerous users over extended periods, amplifying the damage from a single successful attack.
Organizations should implement immediate mitigations including strengthening input validation mechanisms for HTTP headers, implementing proper header sanitization before cache key construction, and deploying additional monitoring to detect anomalous caching behavior. The vulnerability aligns with CWE-444 Web Cache Poisoning which specifically addresses the issue of improper validation of HTTP headers that can lead to cache manipulation. From an ATT&CK perspective, this vulnerability maps to T1566.002 Initial Access: Phishing via Service, as attackers may use poisoned cache responses to deliver malicious payloads to unsuspecting users, and T1584.002 Compromise Infrastructure: Web Service, when attackers leverage the vulnerability to gain control over cached content delivery. Organizations should also consider implementing strict cache control policies, regularly reviewing and testing cache validation logic, and ensuring that all HTTP headers are properly validated before being used in cache-related operations to prevent exploitation of this web cache poisoning vulnerability.