CVE-2018-14055 in ZNC
Summary
by MITRE
ZNC before 1.7.1-rc1 does not properly validate untrusted lines coming from the network, allowing a non-admin user to escalate his privilege and inject rogue values into znc.conf.
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Analysis
by VulDB Data Team • 04/09/2023
The vulnerability identified as CVE-2018-14055 affects ZNC versions prior to 1.7.1-rc1, representing a critical privilege escalation flaw within the ZNC IRC bouncer software. This issue stems from insufficient input validation mechanisms that process untrusted data streams originating from network connections. The vulnerability manifests when the application fails to properly sanitize and validate data received from external sources, creating a pathway for malicious actors to manipulate the configuration system. The flaw specifically targets the configuration file processing mechanism where untrusted input can be injected without proper authorization checks, allowing unauthorized users to modify critical system parameters.
This vulnerability operates under the broader category of improper input validation, which aligns with CWE-20, a well-documented weakness in software security that encompasses various forms of input sanitization failures. The technical implementation flaw occurs within the ZNC application's network processing pipeline where incoming data streams are not adequately filtered or validated before being processed into configuration directives. The vulnerability enables a non-administrative user to inject rogue values into the znc.conf file, effectively bypassing normal access controls and authorization mechanisms that should prevent such modifications. The lack of proper validation creates a condition where malicious input can be interpreted as legitimate configuration commands, leading to unauthorized privilege escalation.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential full system compromise and unauthorized access to IRC communications. Attackers exploiting this vulnerability can inject malicious configuration parameters that may redirect traffic, modify user permissions, or establish backdoor access points within the IRC infrastructure. The configuration file znc.conf serves as a critical control point for the entire ZNC instance, making this vulnerability particularly dangerous as it allows attackers to modify core operational parameters that govern how the bouncer functions. This includes the ability to modify user accounts, adjust network settings, and potentially gain persistent access to the IRC network through manipulated configuration values.
Mitigation strategies for CVE-2018-14055 require immediate patching of affected ZNC installations to version 1.7.1-rc1 or later, which includes proper input validation mechanisms. Organizations should implement network segmentation and access controls to limit exposure of ZNC instances to untrusted networks. The implementation of proper input sanitization techniques, including the use of allowlists for configuration parameters and robust validation of all incoming data streams, should be enforced. Additionally, regular security audits of configuration files and monitoring for unauthorized modifications should be established. This vulnerability demonstrates the importance of following secure coding practices and implementing defense-in-depth strategies as outlined in the ATT&CK framework's privilege escalation techniques, particularly focusing on configuration file manipulation and access control bypass methods. The remediation process should also include comprehensive testing of input validation mechanisms and regular security assessments to prevent similar vulnerabilities from emerging in other components of the IRC infrastructure.