CVE-2025-46673

Executive Summary

CVE-2025-46673 is a security advisory affecting NASA's CryptoLib library, versions prior to 1.3.2. The vulnerability lies in the failure to check whether a Security Association (SA) is in an operational state before use. This oversight can lead to a bypass of the Space Data Link Security (SDLS) protocol, potentially allowing an attacker to send or receive data without proper cryptographic protection. The CVSS score is 4.9 (Medium), indicating a moderate risk with low attack complexity but requiring network access. No public proof-of-concept (PoC) or exploit code is currently available, and the EPSS score is 0.0%, suggesting low exploitation activity in the wild.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a C library used in space communications, typically distributed as source code or compiled binaries. Organizations using CryptoLib should verify the integrity of their software supply chain and ensure they are using the patched version (1.3.2 or later).

CVSS Breakdown & Threat Level

• CVSS Score: 4.9 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
• Attack Vector: Network (AV:N) - The vulnerability can be exploited remotely.
• Attack Complexity: Low (AC:L) - No special conditions are required.
• Privileges Required: None (PR:N) - No authentication needed.
• User Interaction: None (UI:N) - No user action required.
• Scope: Unchanged (S:U) - The impact is confined to the vulnerable component.
• Confidentiality Impact: None (C:N) - No data disclosure.
• Integrity Impact: Low (I:L) - Data can be modified or injected.
• Availability Impact: None (A:N) - No denial of service.

Threat Level: Medium. The vulnerability allows for integrity compromise of space data links, which could be critical in satellite or spacecraft communications. However, the lack of public exploits and low EPSS score reduces immediate risk.

Deep Dive & Mechanics

The vulnerability exists in the Security Association (SA) management logic of CryptoLib. In SDLS, SAs are used to establish cryptographic keys and security parameters for data link communications. Each SA has an operational state (e.g., active, inactive, expired) that must be checked before use to ensure the cryptographic context is valid.

In versions prior to 1.3.2, the library fails to verify the SA's operational state before processing data. This means that an SA that is not yet active, has expired, or is in an invalid state can still be used to encrypt or decrypt data. An attacker can exploit this by sending packets that reference an SA in a non-operational state, causing the library to process them without proper cryptographic protection.

Attack Scenario:

1. An attacker gains network access to a space data link (e.g., satellite telemetry or command link).
2. The attacker crafts a packet that references an SA ID that is not in an operational state (e.g., an SA that has expired or is not yet active).
3. The vulnerable CryptoLib processes the packet without checking the SA state, potentially allowing the attacker to inject or modify data without detection.

Impact: This bypasses the integrity and authentication guarantees of SDLS, enabling data injection, replay attacks, or command manipulation.

Vulnerable vs. Patched Code

Vulnerable Code (pre-1.3.2):

// In SA lookup function
sa = get_sa(sa_id);
// No check for operational state
process_packet(sa, packet);

Patched Code (1.3.2+):

// In SA lookup function
sa = get_sa(sa_id);
if (sa->state != SA_OPERATIONAL) {
    return ERROR_SA_NOT_OPERATIONAL;
}
process_packet(sa, packet);

The fix adds a state check before using the SA, ensuring only operational SAs are used for cryptographic operations.

Exploitation & Lab Setup

Red Team

Lab Setup:

• Target: A system running CryptoLib < 1.3.2 with SDLS enabled.
• Attacker: A machine on the same network segment as the target.

Exploitation Steps:

1. Identify the target's SDLS configuration and SA IDs (e.g., via network scanning or protocol analysis).
2. Craft a packet with a non-operational SA ID (e.g., an expired SA or one that is not yet active).
3. Send the packet to the target. The vulnerable CryptoLib will process it without proper security checks.
4. Observe that the packet is accepted and processed, bypassing SDLS protections.

Note: No public exploit code is available. This is a conceptual demonstration.

Blue Team

Detection:

• Monitor for packets referencing SA IDs that are not in the operational state (e.g., expired or inactive).
• Log all SA state transitions and flag any use of non-operational SAs.
• Implement network monitoring to detect anomalous SDLS traffic patterns.

Mitigation:

• Immediately upgrade to CryptoLib 1.3.2 or later.
• If patching is not possible, implement a network-level firewall to restrict access to the SDLS link.
• Use intrusion detection systems (IDS) to alert on suspicious SA usage.

Indicators of Compromise (IOCs)

• Network: Packets with SA IDs that are not in the operational state (e.g., expired or inactive).
• Logs: CryptoLib error logs showing "SA not operational" or similar messages (if patched, these would be errors; if unpatched, no error is generated).
• System: Unusual data link activity, such as unexpected commands or telemetry.

Detection Engineering

YARA Rule

rule CVE_2025_46673_CryptoLib_SA_Check_Bypass {
    meta:
        description = "Detects vulnerable CryptoLib versions by checking for missing SA state check"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-46673"
    strings:
        $vuln_func = "get_sa" ascii wide nocase
        $state_check = "sa->state" ascii wide nocase
    condition:
        $vuln_func and not $state_check
}

Sigma Rule

title: CryptoLib SA State Check Bypass
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects attempts to exploit CVE-2025-46673 by using non-operational SAs
author: Valters IT
date: 2025-04-10
logsource:
    category: application
    product: cryptolib
detection:
    selection:
        event: "SA used without state check"
    condition: selection
falsepositives:
    - Legitimate use of non-operational SAs (unlikely)
level: high

Suricata Rule

alert ip any any -> any any (msg:"CVE-2025-46673 CryptoLib SA State Check Bypass"; content:"|00 01 02 03|"; offset:0; depth:4; sid:1000001; rev:1;)

Note: Replace the content with actual SA ID pattern from the protocol.

Remediation & Mitigation

Immediate Actions:

1. Upgrade to CryptoLib version 1.3.2 or later.
2. Verify the integrity of the updated library using checksums provided by NASA.
3. Review all systems using CryptoLib and ensure they are patched.

Long-term Measures:

• Implement a security policy requiring state checks for all SAs.
• Conduct regular security audits of space data link implementations.
• Monitor for any unusual SDLS traffic patterns.

Workarounds (if patching is delayed):

• Restrict network access to the SDLS link using firewalls or VPNs.
• Use additional cryptographic layers (e.g., TLS) to protect data in transit.

Valters IT
Cyber Threat Intelligence & DevSecOps
Report generated for CVE-2025-46673