CVE-2020-1664 in Junos
Summary
by MITRE • 10/17/2020
A stack buffer overflow vulnerability in the device control daemon (DCD) on Juniper Networks Junos OS allows a low privilege local user to create a Denial of Service (DoS) against the daemon or execute arbitrary code in the system with root privilege. This issue affects Juniper Networks Junos OS: 17.3 versions prior to 17.3R3-S9; 17.4 versions prior to 17.4R2-S12, 17.4R3-S3; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R3-S6; 18.2X75 versions prior to 18.2X75-D53, 18.2X75-D65; 18.3 versions prior to 18.3R2-S4, 18.3R3-S4; 18.4 versions prior to 18.4R2-S5, 18.4R3-S5; 19.1 versions prior to 19.1R3-S3; 19.2 versions prior to 19.2R1-S5, 19.2R3; 19.3 versions prior to 19.3R2-S4, 19.3R3; 19.4 versions prior to 19.4R1-S3, 19.4R2-S2, 19.4R3; 20.1 versions prior to 20.1R1-S4, 20.1R2; 20.2 versions prior to 20.2R1-S1, 20.2R2. Versions of Junos OS prior to 17.3 are unaffected by this vulnerability.
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Analysis
by VulDB Data Team • 11/20/2020
The vulnerability described in CVE-2020-1664 represents a critical stack buffer overflow within the device control daemon component of Juniper Networks Junos OS operating systems. This flaw exists in the DCD service which handles device control operations and is designed to run with elevated privileges. The buffer overflow occurs when processing certain input data structures, creating an opportunity for malicious code execution or system instability. The vulnerability specifically targets multiple version ranges across Junos OS releases from 17.3 through 20.2, indicating it was present across a significant portion of the product's lifecycle. This widespread impact suggests the flaw was introduced early in the codebase and persisted through numerous release cycles, making it particularly concerning for organizations maintaining legacy deployments. The vulnerability's designation as affecting low privilege local users is significant because it means an attacker with minimal access credentials can potentially escalate privileges to root level, which aligns with the common attack pattern where local privilege escalation vulnerabilities serve as initial access points for broader system compromise.
The technical nature of this vulnerability manifests as a classic stack-based buffer overflow that occurs when the device control daemon processes input data without proper bounds checking. According to CWE standards, this maps directly to CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent stack memory locations. The overflow can potentially overwrite return addresses, function pointers, or other critical control data structures within the stack frame, enabling arbitrary code execution when the function returns. The operational impact extends beyond simple denial of service since the vulnerability can be exploited to execute code with root privileges, effectively providing full system compromise capabilities. This type of vulnerability typically requires the attacker to have local access to the system, but once exploited, the consequences are severe enough to warrant immediate remediation. The fact that this vulnerability affects the device control daemon specifically indicates it's likely triggered through legitimate system management interfaces or control protocols, making detection more challenging.
From a threat modeling perspective, this vulnerability aligns with ATT&CK framework technique T1068 which covers "Exploitation for Privilege Escalation" and T1499 which covers "Endpoint Denial of Service". The attack vector involves a local user leveraging a buffer overflow to gain elevated privileges, which represents a common progression in attack chains where initial access is used to establish a foothold for more extensive compromise. The device control daemon typically operates with high privilege levels to manage system functions, making this a prime target for exploitation. Organizations with multiple Junos OS devices across their network infrastructure face significant risk from this vulnerability, particularly in environments where local access controls are not strictly enforced. The vulnerability affects a broad range of Junos OS versions, indicating that organizations may have been exposed for extended periods without awareness of the risk. The specific version constraints show that patches were released in multiple service releases, suggesting a coordinated patching effort but also indicating that the vulnerability was not immediately recognized as critical by the vendor's security team.
Mitigation strategies for CVE-2020-1664 require immediate implementation of vendor-provided patches across all affected Junos OS versions. Organizations should prioritize patching all impacted systems in their network infrastructure, paying particular attention to devices running older Junos OS versions that may have been overlooked during routine maintenance cycles. Network segmentation and access controls should be reviewed to limit local access to systems running Junos OS, reducing the attack surface for potential exploitation. System monitoring should include detection of unusual processes or activities that might indicate exploitation attempts, particularly around device control daemon operations. Security teams should conduct comprehensive vulnerability assessments to identify all Junos OS devices within their environment and verify patch status. The vulnerability's nature as a stack buffer overflow suggests that input validation and bounds checking improvements in the codebase would be effective preventive measures, though these are not available as immediate fixes for existing deployments. Regular security assessments and vulnerability scanning should be implemented to identify similar issues in other network infrastructure components, as this vulnerability demonstrates how buffer overflow flaws can persist across multiple product versions and release cycles. The affected versions span several years of Junos OS releases, making this a particularly persistent threat that organizations must address through both immediate patching and long-term security process improvements.