CVE-2022-22176 in Junos OS
Summary
by MITRE • 01/19/2022
An Improper Validation of Syntactic Correctness of Input vulnerability in the Juniper DHCP daemon (jdhcpd) of Juniper Networks Junos OS allows an adjacent unauthenticated attacker sending a malformed DHCP packet to cause a crash of jdhcpd and thereby a Denial of Service (DoS). If option-82 is configured in a DHCP snooping / -security scenario, jdhcpd crashes if a specific malformed DHCP request packet is received. The DHCP functionality is impacted while jdhcpd restarts, and continued exploitation of the vulnerability will lead to the unavailability of the DHCP service and thereby a sustained DoS. This issue affects Juniper Networks Junos OS 13.2 version 13.2R1 and later versions prior to 15.1R7-S11; 18.3 versions prior to 18.3R3-S6; 18.4 versions prior to 18.4R2-S9, 18.4R3-S10; 19.1 versions prior to 19.1R2-S3, 19.1R3-S7; 19.2 versions prior to 19.2R1-S8, 19.2R3-S4; 19.3 versions prior to 19.3R2-S7, 19.3R3-S4; 19.4 versions prior to 19.4R3-S6; 20.1 versions prior to 20.1R3-S3; 20.2 versions prior to 20.2R3-S3; 20.3 versions prior to 20.3R3-S1; 20.4 versions prior to 20.4R3; 21.1 versions prior to 21.1R2-S1, 21.1R3; 21.2 versions prior to 21.2R1-S1, 21.2R2. This issue does not affect Juniper Networks Junos OS version 12.3R12 and prior versions.
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Analysis
by VulDB Data Team • 01/20/2022
The vulnerability CVE-2022-22176 represents a critical weakness in Juniper Networks Junos OS affecting the DHCP daemon (jdhcpd) that falls under the category of improper input validation. This flaw manifests when the system processes DHCP packets without adequate syntactic validation, creating an avenue for malicious actors to exploit the system through crafted malformed packets. The vulnerability specifically targets environments where DHCP snooping with option-82 is configured, making it particularly dangerous in network security contexts where such configurations are common. The issue demonstrates how insufficient validation mechanisms in network services can lead to complete service disruption, highlighting the importance of robust input sanitization in critical infrastructure components.
The technical implementation of this vulnerability occurs within the jdhcpd process which handles DHCP requests in Junos OS environments. When a malformed DHCP packet containing specific structures is received, particularly in scenarios where option-82 is enabled, the daemon fails to properly validate the packet syntax and subsequently crashes. This crash occurs because the system lacks proper error handling for malformed input, causing the process to terminate unexpectedly rather than gracefully rejecting the invalid packet. The vulnerability operates at the protocol parsing level, where the DHCP daemon fails to implement adequate bounds checking and input validation routines that would normally prevent such malformed data from causing system instability. This type of flaw aligns with CWE-20, which specifically addresses improper input validation, and represents a classic example of how network services can be made vulnerable through inadequate parsing of external communications.
From an operational perspective, this vulnerability creates a significant denial of service condition that can severely impact network infrastructure availability. The impact extends beyond simple service interruption as the jdhcpd daemon must restart to recover from the crash, resulting in extended periods where DHCP services are unavailable. During this restart period, network devices cannot obtain IP addresses through DHCP, effectively breaking network connectivity for devices relying on dynamic addressing. The sustained nature of the DoS means that continued exploitation can maintain service unavailability until manual intervention occurs or the system restarts naturally. Network administrators face the challenge of identifying and mitigating this vulnerability without disrupting ongoing network operations, particularly in environments where DHCP services are critical to network functionality and where the vulnerability may be exploited by adjacent attackers who have network access.
The affected versions span multiple major releases of Junos OS, indicating this vulnerability has persisted across several years of development cycles and suggests a fundamental flaw in the input validation implementation. The specific version ranges show that the vulnerability affects releases from 13.2R1 through various patch levels of 20.x and 21.x series, with the exception of older versions 12.3R12 and prior. This wide scope of affected versions demonstrates how input validation flaws can remain undetected for extended periods, particularly when they only manifest under specific configuration scenarios such as DHCP snooping with option-82. The vulnerability's presence in multiple patch levels suggests that the fix was not consistently applied across all release branches, creating ongoing exposure for organizations maintaining older patched versions. Organizations should consider implementing immediate mitigation strategies including network segmentation to prevent adjacent attackers from reaching affected systems, disabling DHCP snooping when possible, or applying the appropriate security patches to address the specific validation issues in the jdhcpd daemon.
The ATT&CK framework categorizes this vulnerability under T1499.004 for Network Denial of Service and T1071.004 for Application Layer Protocol, as it exploits weaknesses in application-level protocols to cause service disruption. The vulnerability also aligns with the concept of privilege escalation through service exploitation, where an unauthenticated attacker can gain control over critical network services. Organizations should implement monitoring for unusual DHCP traffic patterns and establish incident response procedures specifically for DHCP service disruptions. The vulnerability highlights the importance of comprehensive security testing including fuzzing and input validation testing of network services, particularly those handling external communications. This weakness serves as a reminder of the critical need for regular security assessments and patch management processes to prevent exploitation of known vulnerabilities in network infrastructure components.