CVE-2024-21616 Explained : Impact and Mitigation

This CVE involves an Improper Validation of Syntactic Correctness of Input vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS. It allows an unauthenticated attacker to trigger a Denial of Service (DoS) by causing NAT IP allocation to fail on MX Series and SRX Series platforms when SIP ALG is enabled.

Understanding CVE-2024-21616

This vulnerability impacts Juniper Networks Junos OS on MX Series and SRX Series. A specific SIP packet, when processed with enabled SIP ALG, triggers the issue leading to a sustained DoS condition.

What is CVE-2024-21616?

The CVE refers to an Improper Validation of Syntactic Correctness of Input vulnerability in Juniper Networks Junos OS, allowing unauthenticated attackers to execute a DoS attack by causing NAT IP allocation failure.

The Impact of CVE-2024-21616

When SIP ALG is enabled, genuine traffic may experience NAT IP allocation issues, leading to a denial of service condition. Furthermore, continuous receipt of the specific SIP ALG packet exacerbates the DoS situation.

Technical Details of CVE-2024-21616

This vulnerability affects various versions of Junos OS on MX Series and SRX Series platforms.

Vulnerability Description

The vulnerability stems from improper validation in the Packet Forwarding Engine, allowing network-based attackers to exploit the issue for DoS attacks.

Affected Systems and Versions

All versions earlier than 21.2R3-S6
21.3 versions earlier than 21.3R3-S5
21.4 versions earlier than 21.4R3-S5
22.1 versions earlier than 22.1R3-S4
22.2 versions earlier than 22.2R3-S3
22.3 versions earlier than 22.3R3-S1
22.4 versions earlier than 22.4R2-S2, 22.4R3
23.2 versions earlier than 23.2R1-S1, 23.2R2

Exploitation Mechanism

As of now, Juniper SIRT has not detected any malicious exploits targeting this vulnerability.

Mitigation and Prevention

To address CVE-2024-21616, immediate steps and long-term security practices are necessary.

Immediate Steps to Take

Monitor NAT IP usage and disable SIP ALG if unnecessary to mitigate the risk of DoS attacks.

Long-Term Security Practices

Regularly update Junos OS to the patched versions provided by Juniper Networks to prevent exploitation of this vulnerability.

Patching and Updates

Juniper Networks has released updated software versions to resolve the issue. Update to Junos OS 21.2R3-S6, 21.3R3-S5, 21.4R3-S5, 22.1R3-S4, 22.2R3-S3, 22.3R3-S1, 22.4R2-S2, 22.4R3, 23.2R1-S1, 23.2R2, 23.4R1, or later releases.

Please refer to the Juniper advisory JSA75757 for detailed information on this vulnerability.