CVE-2024-45238 in Fort
Summary
by MITRE • 08/25/2024
An issue was discovered in Fort before 1.6.3. A malicious RPKI repository that descends from a (trusted) Trust Anchor can serve (via rsync or RRDP) a resource certificate containing a bit string that doesn't properly decode into a Subject Public Key. OpenSSL does not report this problem during parsing, and when compiled with OpenSSL libcrypto versions below 3, Fort recklessly dereferences the pointer. Because Fort is an RPKI Relying Party, a crash can lead to Route Origin Validation unavailability, which can lead to compromised routing.
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Analysis
by VulDB Data Team • 02/24/2025
The vulnerability identified as CVE-2024-45238 affects Fort versions prior to 1.6.3, representing a critical security flaw in RPKI (Resource Public Key Infrastructure) validation systems. This issue stems from improper handling of malformed resource certificates within the RPKI repository hierarchy, specifically when a malicious repository that descends from a trusted Trust Anchor serves certificates containing malformed bit strings. The vulnerability exploits a fundamental weakness in how Fort processes cryptographic key material, creating a potential pathway for route hijacking and routing security compromise. The flaw manifests when the system attempts to process resource certificates that contain bit strings which fail to properly decode into valid Subject Public Key information.
The technical implementation of this vulnerability involves a pointer dereference error that occurs when Fort processes RPKI certificates through its reliance on OpenSSL libcrypto. When compiled with OpenSSL versions below 3, the system fails to properly validate certificate integrity during parsing, allowing malformed bit strings to pass through undetected. This oversight creates a condition where Fort recklessly dereferences a pointer that should have been validated or rejected during certificate processing, leading to system instability. The vulnerability specifically targets the RPKI relying party functionality, where Fort acts as a client validating route origin information from RPKI repositories. The absence of proper validation during certificate parsing means that malformed certificates can cause memory access violations and system crashes.
The operational impact of this vulnerability extends beyond simple system instability to threaten the fundamental integrity of Internet routing infrastructure. When Fort crashes due to processing the malformed certificate, it results in unavailability of Route Origin Validation services, which are critical for preventing unauthorized route announcements. This disruption can lead to compromised routing decisions where malicious actors could potentially announce routes for IP prefixes they do not legitimately own, enabling various attack vectors including prefix hijacking and traffic interception. The vulnerability creates a scenario where a single malicious repository can compromise the entire RPKI validation ecosystem for systems relying on Fort, as the crash propagates through the trust chain from the trusted anchor to the relying party systems.
Organizations using Fort for RPKI validation should prioritize immediate patching to version 1.6.3 or later, which addresses the pointer dereference issue through improved certificate validation routines. The fix implements proper validation of bit string decoding before attempting cryptographic operations, preventing the reckless pointer dereference that previously caused crashes. Additionally, system administrators should consider implementing monitoring for RPKI repository behavior and establish incident response procedures for detecting and mitigating malicious repository activity. The vulnerability aligns with CWE-476 which describes "NULL Pointer Dereference" and demonstrates characteristics consistent with ATT&CK technique T1583.001 related to developing capabilities for credential access and T1071.004 for application layer protocols. Organizations should also consider implementing redundant validation systems and diversifying their RPKI repository sources to minimize risk from single points of failure in the validation infrastructure.