CVE-2020-3483 in Network Gateway
Summary
by MITRE • 10/15/2020
Duo has identified and fixed an issue with the Duo Network Gateway (DNG) product in which some customer-provided SSL certificates and private keys were not excluded from logging. This issue resulted in certificate and private key information being written out in plain-text to local files on the DNG host. Any private keys logged in this way could be viewed by those with access to the DNG host operating system without any need for reversing encrypted values or similar techniques. An attacker that gained access to the DNG logs and with the ability to intercept and manipulate network traffic between a user and the DNG, could decrypt and manipulate SSL/TLS connections to the DNG and to the protected applications behind it. Duo Network Gateway (DNG) versions 1.3.3 through 1.5.7 are affected.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 11/20/2020
The vulnerability identified as CVE-2020-3483 represents a critical security flaw in Duo Network Gateway (DNG) versions 1.3.3 through 1.5.7 where sensitive cryptographic materials were inadvertently logged in plain text format. This issue stems from inadequate input validation and logging practices within the DNG product, specifically failing to sanitize or exclude SSL certificates and private keys from system logs. The flaw manifests when customer-provided SSL certificates and private keys are processed by the DNG and subsequently written to local log files without proper obfuscation or filtering mechanisms. This represents a fundamental failure in the principle of least privilege and secure logging practices, creating an information disclosure vulnerability that directly violates security best practices outlined in industry standards such as those defined by CWE-532 which addresses information exposure through log files.
The technical implementation of this vulnerability allows for complete compromise of cryptographic security when attackers gain access to the DNG host's file system. Private keys and certificate information stored in plain text within log files eliminate the need for advanced cryptanalysis or reverse engineering techniques, as the sensitive materials are directly accessible to any entity with operating system-level access. The impact extends beyond simple information disclosure, as the presence of private keys in logs enables man-in-the-middle attacks and session hijacking capabilities. Attackers with access to the DNG logs can decrypt SSL/TLS traffic flowing through the gateway, potentially compromising all encrypted communications between users and protected applications. This vulnerability directly maps to ATT&CK technique T1071.004 for Application Layer Protocol: DNS and T1566 for Phishing, as compromised certificates can be used to establish trusted communication channels for malicious activities.
The operational impact of this vulnerability is severe and multifaceted, affecting organizations that rely on DNG for network security and access control. The compromise of private keys through plain text logging creates an immediate risk to the integrity and confidentiality of all communications passing through the gateway. Organizations may face regulatory compliance violations under standards such as PCI DSS, HIPAA, and GDPR, which mandate protection of cryptographic keys and sensitive information. The vulnerability's exploitation requires minimal technical sophistication, as attackers only need local file system access to retrieve the sensitive materials. Network administrators must consider that this flaw could enable attackers to establish persistent access to protected applications and systems, potentially leading to broader compromise of the network infrastructure. The affected versions span a significant release range, indicating this was likely a long-standing issue that affected numerous organizations using the DNG platform for security operations.
Mitigation strategies for CVE-2020-3483 require immediate action including patching the DNG software to versions that properly sanitize logging output and prevent cryptographic materials from being written to log files. Organizations should implement strict access controls on DNG host systems, limiting file system access to authorized personnel only, and establish regular log monitoring procedures to detect unauthorized access attempts. Security teams must conduct comprehensive audits of existing DNG installations to identify and remove any previously logged private keys, implementing key rotation procedures for affected systems. The remediation process should include disabling or configuring logging to exclude sensitive data, implementing log file permissions controls, and establishing automated monitoring for potential unauthorized access to log files. Additionally, organizations should consider implementing network segmentation and additional security controls around the DNG infrastructure to limit the attack surface and reduce the impact of potential compromise. The vulnerability highlights the critical importance of secure logging practices and proper input sanitization as outlined in security frameworks such as NIST SP 800-53 and ISO/IEC 27001 controls for information security management.