CVE-2023-50434 in simple-dhcp-server
Summary
by MITRE • 04/30/2024
emdns_resolve_raw in emdns.c in emdns through fbd1eef calls strlen with an input that may not be '\0' terminated, leading to a stack-based buffer over-read. This can be triggered by a remote adversary that can send DNS requests to the emdns server. The impact could vary depending on the system libraries, compiler, and processor architecture. Code before be565c3 is unaffected.
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Analysis
by VulDB Data Team • 04/30/2024
The vulnerability identified as CVE-2023-50434 resides within the emdns software library, specifically in the emdns_resolve_raw function located in the emdns.c source file. This issue represents a classic stack-based buffer over-read condition that emerges from improper handling of string input validation. The flaw occurs when the function invokes the strlen() system call on data that may not be properly null-terminated, creating a dangerous scenario where memory beyond the intended buffer boundaries gets accessed. This type of vulnerability falls under the Common Weakness Enumeration category CWE-121, which encompasses stack-based buffer overflow conditions that can lead to arbitrary code execution or information disclosure. The emdns library serves as a DNS resolution component that processes incoming DNS requests, making it a critical element in network infrastructure systems that handle external communication.
Remote adversaries can exploit this vulnerability by sending specially crafted DNS requests to the emdns server, effectively triggering the flawed code path without requiring local system access or authentication. The attack vector is particularly concerning because it operates entirely over the network protocol layer, allowing threat actors to leverage this weakness from external positions. The exploitation potential varies significantly based on system characteristics including the specific system libraries in use, compiler optimizations applied during build processes, and the underlying processor architecture. Different combinations of these environmental factors can produce varying outcomes ranging from simple denial of service conditions to more severe scenarios involving memory corruption that could enable remote code execution. The vulnerability affects emdns versions up to and including fbd1eef, with code modifications beginning from commit be565c3 providing protection against this specific issue.
The operational impact of CVE-2023-50434 extends beyond immediate system compromise to encompass broader network security implications. Systems utilizing vulnerable emdns implementations become susceptible to unauthorized access and potential data exfiltration, particularly in environments where DNS resolution services are exposed to untrusted networks. The vulnerability's remote exploitability means that organizations cannot rely solely on network segmentation or firewall rules to protect against this threat, as the attack can originate from any location capable of sending DNS requests to the target server. Security practitioners should consider this vulnerability in the context of the MITRE ATT&CK framework, specifically under the T1071.004 technique for application layer protocol: DNS, where adversaries leverage DNS infrastructure for command and control communications or data exfiltration. The issue demonstrates how seemingly benign network services can become attack vectors when proper input validation and memory management practices are not implemented.
Mitigation strategies for CVE-2023-50434 should prioritize immediate software updates to versions containing the fix introduced in commit be565c3, which properly addresses the null-termination issue in the emdns_resolve_raw function. Organizations should also implement network monitoring to detect anomalous DNS request patterns that might indicate exploitation attempts, particularly focusing on unusual query types or malformed DNS packets. Additional protective measures include deploying intrusion detection systems with signature-based detection for known exploit patterns, implementing proper input validation at network boundaries, and conducting thorough vulnerability assessments of all systems utilizing emdns or similar DNS resolution libraries. Security teams should consider the principle of least privilege when configuring emdns services, limiting the exposure of DNS resolution capabilities to only necessary network segments. The vulnerability serves as a reminder of the critical importance of proper memory management in network services and the necessity of rigorous code review processes that specifically examine string handling and buffer boundary conditions. Organizations should also establish robust patch management procedures to ensure timely deployment of security fixes across all network infrastructure components.