CVE-2020-1688 in Junos
Summary
by MITRE • 10/17/2020
On Juniper Networks SRX Series and NFX Series, a local authenticated user with access to the shell may obtain the Web API service private key that is used to provide encrypted communication between the Juniper device and the authenticator services. Exploitation of this vulnerability may allow an attacker to decrypt the communications between the Juniper device and the authenticator service. This Web API service is used for authentication services such as the Juniper Identity Management Service, used to obtain user identity for Integrated User Firewall feature, or the integrated ClearPass authentication and enforcement feature. This issue affects Juniper Networks Junos OS on Networks SRX Series and NFX Series: 12.3X48 versions prior to 12.3X48-D105; 15.1X49 versions prior to 15.1X49-D190; 16.1 versions prior to 16.1R7-S8; 17.2 versions prior to 17.2R3-S4; 17.3 versions prior to 17.3R3-S8; 17.4 versions prior to 17.4R2-S11, 17.4R3; 18.1 versions prior to 18.1R3-S7; 18.2 versions prior to 18.2R3; 18.3 versions prior to 18.3R2-S4, 18.3R3; 18.4 versions prior to 18.4R1-S7, 18.4R2; 19.1 versions prior to 19.1R2; 19.2 versions prior to 19.2R1-S4, 19.2R2.
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Analysis
by VulDB Data Team • 11/20/2020
The vulnerability described in CVE-2020-1688 represents a critical security flaw in Juniper Networks SRX and NFX series devices running Junos OS. This issue affects multiple software versions across different release branches, specifically targeting the Web API service that facilitates encrypted communication between network devices and authentication services. The vulnerability stems from inadequate privilege separation and improper key management practices within the device's authentication infrastructure, creating a pathway for local authenticated users to access sensitive cryptographic materials.
The technical implementation of this vulnerability involves a local privilege escalation scenario where an authenticated user with shell access can exploit a weakness in the system's key storage mechanism. The Web API service private key, which serves as the cryptographic foundation for secure communication between Juniper devices and authenticator services, becomes accessible to unauthorized local users. This exposure directly violates fundamental security principles of key management and privilege separation, as outlined in CWE-310 - Cryptographic Issues and CWE-276 - Incorrect Permissions for Critical Resources.
The operational impact of this vulnerability extends beyond simple credential theft, as it compromises the integrity of the entire authentication ecosystem. Attackers who successfully exploit this vulnerability can decrypt communications between network devices and authentication services such as Juniper Identity Management Service and ClearPass authentication systems. This capability enables man-in-the-middle attacks, session hijacking, and potential elevation of privileges within the network infrastructure. The vulnerability affects core authentication features including Integrated User Firewall functionality, which relies on secure identity verification for access control decisions.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1552 - Unsecured Credentials and T1078 - Valid Accounts, as it allows attackers to leverage legitimate authentication mechanisms through compromised cryptographic keys. The affected versions span multiple Junos OS releases, indicating a persistent flaw in the key management implementation that required patching across several major version lines. Organizations using Juniper SRX and NFX series devices must understand that this vulnerability creates a persistent backdoor for attackers who gain local shell access, as the private key remains accessible even after system reboots.
Mitigation strategies should prioritize immediate patching of affected devices to the recommended Junos OS versions, which address the underlying key storage vulnerabilities. Network administrators should implement strict access controls to prevent unauthorized shell access, including disabling unnecessary administrative accounts and enforcing multi-factor authentication for privileged access. Additionally, organizations should conduct comprehensive security assessments to identify any potential exploitation attempts and monitor network traffic for signs of decrypted authentication communications. The vulnerability demonstrates the critical importance of proper cryptographic key management practices and highlights the need for regular security audits of authentication infrastructure components.