CVE-2024-29937 Overview
CVE-2024-29937 is a critical remote code execution vulnerability affecting the Network File System (NFS) implementation in BSD-derived codebases, specifically impacting OpenBSD through version 7.4 and FreeBSD through 14.0-RELEASE. This vulnerability is notably characterized as being unrelated to memory corruption, suggesting a logic flaw or code injection vector in the NFS protocol handling that allows remote attackers to execute arbitrary code on vulnerable systems.
Critical Impact
Remote attackers can execute arbitrary code on affected BSD systems without requiring authentication or user interaction, potentially leading to complete system compromise.
Affected Products
- OpenBSD through version 7.4
- FreeBSD through version 14.0-RELEASE
- Other BSD-derived systems sharing the affected NFS codebase
Discovery Timeline
- 2024-04-11 - CVE-2024-29937 published to NVD
- 2025-06-17 - Last updated in NVD database
Technical Details for CVE-2024-29937
Vulnerability Analysis
This vulnerability is classified as CWE-94 (Improper Control of Generation of Code), indicating a code injection vulnerability within the NFS implementation. The explicit mention that this bug is "unrelated to memory corruption" distinguishes it from typical buffer overflow or use-after-free vulnerabilities commonly found in network protocol implementations.
The NFS protocol is designed to allow remote file system access over a network, making it a high-value target for attackers. When NFS implementations fail to properly validate or sanitize input during protocol handling, attackers can inject malicious code that executes in the context of the NFS service, which typically runs with elevated privileges.
Root Cause
The root cause is improper control of code generation (CWE-94) within the NFS protocol handling code shared across BSD-derived operating systems. This suggests that user-controlled input is being processed in a way that allows for the generation or execution of arbitrary code, bypassing traditional memory safety mechanisms.
Attack Vector
The attack can be executed remotely over the network without requiring authentication or user interaction. An attacker with network access to an NFS service running on a vulnerable OpenBSD or FreeBSD system can exploit this vulnerability to achieve arbitrary code execution. Given the nature of NFS services, which often run with root or elevated privileges, successful exploitation could lead to complete system compromise.
The vulnerability has been discussed in security research circles, with presentations at T2.fi 2024 and related discussions on platforms like Hacker News providing additional context on the technical nature of this flaw.
Detection Methods for CVE-2024-29937
Indicators of Compromise
- Unusual NFS traffic patterns or malformed NFS requests targeting vulnerable systems
- Unexpected process spawning from NFS-related daemons (nfsd, mountd)
- Anomalous network connections originating from systems running NFS services
- Log entries indicating NFS protocol errors or unexpected behavior
Detection Strategies
- Monitor NFS service logs for unusual activity or error patterns that may indicate exploitation attempts
- Deploy network intrusion detection systems (NIDS) with rules to identify anomalous NFS protocol traffic
- Implement behavioral analysis on NFS server processes to detect unexpected code execution
- Audit systems running OpenBSD through 7.4 or FreeBSD through 14.0-RELEASE for NFS exposure
Monitoring Recommendations
- Enable verbose logging for NFS-related services and forward logs to a centralized SIEM
- Monitor for new or unexpected child processes spawned by NFS daemons
- Track network connections to NFS ports (typically TCP/UDP 2049) from untrusted sources
- Implement file integrity monitoring on critical system binaries and NFS configurations
How to Mitigate CVE-2024-29937
Immediate Actions Required
- Restrict NFS access to trusted networks only using firewall rules
- Disable NFS services if not required for business operations
- Upgrade to patched versions of OpenBSD or FreeBSD as they become available
- Implement network segmentation to limit exposure of NFS services
Patch Information
Organizations running affected versions of OpenBSD (through 7.4) or FreeBSD (through 14.0-RELEASE) should monitor their respective security advisory channels for official patches. Consult the Hacker News Discussion and Signedness T2.fi Overview for additional technical context on the vulnerability and potential mitigations.
Workarounds
- Implement strict firewall rules to limit NFS access to trusted IP addresses only
- Consider using VPN tunnels for NFS traffic to add an additional layer of authentication
- Deploy application-layer firewalls capable of inspecting NFS protocol traffic
- Temporarily disable NFS services on internet-facing systems until patches are applied
# FreeBSD: Restrict NFS access via firewall (ipfw example)
ipfw add deny tcp from any to me 2049
ipfw add deny udp from any to me 2049
ipfw add allow tcp from 10.0.0.0/8 to me 2049
ipfw add allow udp from 10.0.0.0/8 to me 2049
# OpenBSD: Restrict NFS access via pf.conf
# Add to /etc/pf.conf:
# block in quick on egress proto { tcp, udp } to port 2049
# pass in on egress proto { tcp, udp } from 10.0.0.0/8 to port 2049
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
