CVE-2021-0217 is a high-severity vulnerability in the processing of certain DHCP packets from adjacent clients on Juniper Networks' EX Series and QFX Series switches running Junos OS. This vulnerability allows for the exhaustion of Direct Memory Access (DMA) memory, potentially leading to a Denial of Service (DoS). Over time, exploitation of this vulnerability may cause traffic to stop being forwarded or result in the crashing of the fxpc process.
The CVSS score for this vulnerability is 7.4, indicating a high level of severity. Its impact is primarily on availability, with an availability impact score of high. Organizations using the affected Junos OS versions should prioritize patching to mitigate the risk of exploitation.
As of now, there are no known exploits for this vulnerability, and it is not included in the Known Exploited Vulnerabilities (KEV) catalog. Organizations are advised to remain vigilant and apply the relevant patches as soon as they are available.
Organizations should prioritize patching immediately to prevent potential disruption to their network services.
Vulnerability Details
The vulnerability arises from the processing of DHCP packets when a DHCP local/relay server is configured on Junos OS. The exhaustion of DMA memory leads to instability of the Packet DMA heap, which can be monitored with specific commands. The issue is indicated by failure messages in the logs, suggesting that packet buffer allocation has failed.
Affected versions include Junos OS 17.4R3 prior to 17.4R3-S3, 18.1R3 between 18.1R3-S6 and 18.1R3-S11, and multiple versions up to 20.2R1-S2. Any versions prior to 17.4R3 are unaffected.
Technical Analysis
The root cause of this vulnerability is improper handling of DHCP packets, which leads to memory exhaustion. The attack vector is adjacent network access, allowing attackers with local access to potentially exploit the vulnerability. The attack complexity is low, requiring no special privileges or user interaction.
When the DMA heap utilization reaches critical levels (99%), the system becomes unstable, which can result in denial of service for legitimate traffic. The impacts on confidentiality and integrity are none, but the availability impact is significant, warranting immediate attention from affected organizations.
Risk & Impact Analysis
Risk to organizations includes service interruptions and potential downtime due to the instability caused by this vulnerability. The blast radius of an attack exploiting this vulnerability could affect all services dependent on the Junos OS, impacting business operations significantly.
Organizations should address this vulnerability in their priority patch cycle, especially those relying on Junos OS for critical networking functions. The current exploitability score suggests a moderate risk, but the potential for high-impact availability issues necessitates prompt remediation.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
This vulnerability affects the following versions of Junos OS: 17.4R3 versions prior to 17.4R3-S3; 18.1R3 versions between 18.1R3-S6 and 18.1R3-S11; 18.2R3 versions prior to 18.2R3-S6; 18.3R3 versions prior to 18.3R3-S4; 18.4R2 versions prior to 18.4R2-S5; 18.4R3 versions prior to 18.4R3-S6; 19.1 versions between 19.1R2 and 19.1R3-S3; 19.2 versions prior to 19.2R3-S1; 19.3 versions prior to 19.3R2-S5, 19.3R3; 19.4 versions prior to 19.4R2-S2, 19.4R3; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R1-S2, 20.2R2.
Mitigation & Remediation
Organizations should upgrade to the latest patched versions of Junos OS to mitigate this vulnerability. If patches are not immediately available, it is advisable to monitor DMA heap utilization closely and apply configuration hardening measures to minimize exposure.
For more comprehensive security assessments, organizations can consider application security assessments to identify similar vulnerabilities.
Detection Guidance
Monitoring logs for specific failure messages related to packet buffer allocation will aid in detecting potential exploitation attempts. Additionally, organizations should watch for any unusual spikes in DMA heap utilization that could indicate an ongoing attack.
AppSecure Threat Intelligence Insight
The long-term significance of CVE-2021-0217 lies in its demonstration of how mismanagement of memory resources can lead to critical service disruptions. Security teams should learn from this incident to enhance their response protocols and preventive measures against potential DoS attacks.
Organizations should also consider reviewing their risk management strategies and invest in penetration testing services to proactively identify and remediate similar vulnerabilities.
Regularly updating security protocols in line with emerging threats is essential, and maintaining awareness of vulnerabilities like CVE-2021-0217 can help organizations fortify their defenses.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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