CVE-2023-38505 in DietPi-Dashboard
Summary
by MITRE • 07/27/2023
DietPi-Dashboard is a web dashboard for the operating system DietPi. The dashboard only allows for one TLS handshake to be in process at a given moment. Once a TCP connection is established in HTTPS mode, it will assume that it should be waiting for a handshake, and will stay this way indefinitely until a handshake starts or some error occurs. In version 0.6.1, this can be exploited by simply not starting the handshake, preventing any other TLS handshakes from getting through. An attacker can lock the dashboard in a state where it is waiting for a TLS handshake from the attacker, who won't provide it. This prevents any legitimate traffic from getting to the dashboard, and can last indefinitely. Version 0.6.2 has a patch for this issue. As a workaround, do not use HTTPS mode on the open internet where anyone can connect. Instead, put a reverse proxy in front of the dashboard, and have it handle any HTTPS connections.
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Analysis
by VulDB Data Team • 07/27/2023
The vulnerability described in CVE-2023-38505 affects DietPi-Dashboard, a web interface designed for the DietPi operating system that provides administrative capabilities for managing embedded devices. This dashboard operates with a critical concurrency limitation in its TLS implementation that creates a persistent denial of service condition. The flaw manifests as a single-threaded TLS handshake mechanism that processes only one connection at a time, fundamentally breaking the expected behavior of a web server handling multiple concurrent connections. The implementation follows a sequential processing model where each TCP connection is treated as a potential TLS handshake candidate, creating a queue-like behavior that can be exploited maliciously.
The technical exploitation of this vulnerability stems from a race condition and resource exhaustion pattern that directly maps to CWE-400, which addresses unspecified denial of service conditions. When an attacker establishes a TCP connection to the dashboard in HTTPS mode without completing the TLS handshake, the system enters an indefinite waiting state where it continuously awaits the handshake completion. This creates a resource bottleneck where legitimate connection attempts cannot proceed because the system is locked in a state expecting the incomplete handshake. The vulnerability specifically affects the TLS handshake processing logic that lacks proper timeout mechanisms or connection state management, allowing a single malicious connection to block all subsequent legitimate traffic. The flaw represents a classic case of insufficient resource management where the system's inability to handle concurrent connections leads to a complete service denial.
The operational impact of this vulnerability extends beyond simple service disruption to create a persistent availability issue that can last indefinitely until the vulnerable system is manually restarted or the blocking connection is terminated. Legitimate users attempting to access the dashboard experience complete inability to establish connections, effectively locking them out of the system's administrative interface. This represents a critical security risk for embedded systems where remote administration is essential for device maintenance and configuration. The vulnerability particularly affects environments where the dashboard is exposed to untrusted networks or the open internet, as attackers can easily exploit this condition without requiring elevated privileges or complex attack vectors. The impact is amplified in IoT and embedded device deployments where physical access to restart the system may not be readily available, creating extended periods of service unavailability.
Mitigation strategies for this vulnerability should focus on both immediate defensive measures and architectural improvements. The most straightforward approach involves implementing a reverse proxy solution such as nginx or Apache to handle HTTPS termination and connection management before forwarding requests to the vulnerable dashboard. This architectural pattern aligns with ATT&CK technique T1190, which addresses the use of proxies to obscure the true location of services and reduce direct exposure to attack vectors. Additionally, administrators should disable HTTPS mode when the dashboard is exposed to public networks, relying instead on internal network access or proper security controls. The patch implemented in version 0.6.2 addresses the core concurrency issue by modifying the TLS handshake processing to properly handle multiple simultaneous connections or implement appropriate timeout mechanisms. Organizations should also consider implementing connection rate limiting and proper timeout configurations to prevent similar issues in other network services, following security best practices outlined in NIST SP 800-44 for web application security and the OWASP Top Ten for web application vulnerabilities.