CVE-2025-29913 in CryptoLib
Summary
by MITRE • 03/18/2025
CryptoLib provides a software-only solution using the CCSDS Space Data Link Security Protocol - Extended Procedures (SDLS-EP) to secure communications between a spacecraft running the core Flight System (cFS) and a ground station. A critical heap buffer overflow vulnerability was identified in the `Crypto_TC_Prep_AAD` function of CryptoLib versions 1.3.3 and prior. This vulnerability allows an attacker to trigger a Denial of Service (DoS) or potentially execute arbitrary code (RCE) by providing a maliciously crafted telecommand (TC) frame that causes an unsigned integer underflow. The vulnerability lies in the function `Crypto_TC_Prep_AAD`, specifically during the computation of `tc_mac_start_index`. The affected code incorrectly calculates the MAC start index without ensuring it remains within the bounds of the `ingest` buffer. When `tc_mac_start_index` underflows due to an incorrect length calculation, the function attempts to access an out-of-bounds memory location, leading to a segmentation fault. The vulnerability is still present in the repository as of commit `d3cc420ace96d02a5b7e83d88cbd2e48010d5723`.
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Analysis
by VulDB Data Team • 03/18/2025
The vulnerability described in CVE-2025-29913 represents a critical heap buffer overflow within CryptoLib's implementation of the CCSDS Space Data Link Security Protocol - Extended Procedures, a security framework specifically designed for protecting communications between spacecraft running the core Flight System and ground stations. This software solution operates in highly sensitive environments where reliable communication is paramount for mission success and safety. The vulnerability exists in versions 1.3.3 and earlier of the library, making it a persistent threat across multiple releases of this critical space communications software. The issue manifests in the `Crypto_TC_Prep_AAD` function which processes telecommand frames destined for spacecraft operations, creating a potential attack surface that could severely impact mission-critical systems.
The technical flaw stems from an unsigned integer underflow condition within the memory management logic of the `Crypto_TC_Prep_AAD` function, specifically during the calculation of `tc_mac_start_index`. This function is responsible for preparing the Additional Authenticated Data (AAD) portion of the security processing, which is crucial for maintaining data integrity and authenticity in space communications. The vulnerability occurs when the system attempts to compute the MAC start index without proper bounds checking against the `ingest` buffer, allowing an attacker to craft a malicious telecommand frame that triggers an unsigned integer underflow. This mathematical error causes the calculated index to wrap around to a very large positive value, resulting in an attempt to access memory locations far beyond the intended buffer boundaries. The underlying issue is a classic buffer overflow condition that violates the fundamental principle of memory safety, where the system fails to validate that computed memory addresses remain within allocated buffer limits.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, presenting potential for remote code execution that could compromise entire spacecraft systems. When an attacker successfully triggers the unsigned integer underflow, the system experiences a segmentation fault due to accessing invalid memory addresses, which can result in system crashes or unpredictable behavior. However, the more concerning aspect is that this vulnerability could potentially be exploited for arbitrary code execution, allowing malicious actors to gain control over spacecraft operations and potentially manipulate mission-critical data flows. This risk is particularly severe in space environments where system recovery may be impossible and where compromised communications could lead to mission failure, data loss, or even safety hazards for ground personnel and satellite operations. The vulnerability's presence in the repository as of commit d3cc420ace96d02a5b7e83d88cbd2e48010d5723 indicates that the flaw has not been addressed in the codebase, leaving systems using this library exposed to ongoing exploitation attempts.
The vulnerability maps directly to CWE-121, which describes heap-based buffer overflow conditions, and aligns with ATT&CK technique T1547.001 for privilege escalation through code injection. Organizations implementing this library should immediately implement mitigations including input validation of telecommand frames, bounds checking in the `Crypto_TC_Prep_AAD` function, and proper integer overflow protection mechanisms. The recommended remediation involves adding explicit bounds checking before the MAC start index calculation, ensuring that all computed memory addresses remain within valid buffer boundaries, and implementing comprehensive testing procedures to verify that malicious inputs cannot trigger the underflow condition. Additionally, organizations should consider implementing network segmentation and access controls to limit exposure, while monitoring for potential exploitation attempts in their space communication systems. The vulnerability demonstrates the critical importance of memory safety in embedded systems and highlights the need for rigorous security testing in mission-critical software environments where traditional software security practices must be adapted for the unique challenges of space operations and real-time systems.