CVE-2007-5365 in OpenBSD
Summary
by MITRE
Stack-based buffer overflow in the cons_options function in options.c in dhcpd in OpenBSD 4.0 through 4.2, and some other dhcpd implementations based on ISC dhcp-2, allows remote attackers to execute arbitrary code or cause a denial of service (daemon crash) via a DHCP request specifying a maximum message size smaller than the minimum IP MTU.
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Analysis
by VulDB Data Team • 10/10/2024
The vulnerability identified as CVE-2007-5365 represents a critical stack-based buffer overflow affecting the dhcpd daemon in OpenBSD versions 4.0 through 4.2 and other implementations derived from ISC dhcp-2. This flaw resides within the cons_options function in the options.c file, demonstrating a classic software security weakness that can be exploited to gain unauthorized system control or disrupt service availability. The vulnerability specifically manifests when processing DHCP requests that specify a maximum message size parameter smaller than the minimum IP MTU, creating a condition where attacker-controlled data exceeds the bounds of a fixed-size stack buffer.
The technical implementation of this vulnerability stems from inadequate input validation within the DHCP option processing logic. When dhcpd receives a malformed DHCP request containing a message size parameter below the IP MTU threshold, the cons_options function fails to properly bounds-check the incoming data before copying it into a stack-allocated buffer. This buffer overflow condition allows attackers to overwrite adjacent stack memory locations, potentially corrupting the return address or other critical execution context. The flaw operates at the application layer of the network stack, making it particularly dangerous as it requires no privileged access to exploit and can be triggered through standard network communication with the targeted DHCP server.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to encompass full remote code execution capabilities. Attackers exploiting this vulnerability can potentially overwrite the program's execution flow to redirect control to malicious code injected into the stack, enabling arbitrary command execution with the privileges of the dhcpd process. The daemon crash resulting from the buffer overflow also constitutes a denial of service attack that can disrupt network services, particularly in environments where DHCP serves as a critical infrastructure component. This vulnerability affects not only OpenBSD systems but also other implementations based on the ISC dhcp-2 codebase, indicating a widespread exposure across various network infrastructure deployments.
Security mitigations for this vulnerability should focus on immediate patch application to address the root cause within the dhcpd implementation. Organizations must ensure all affected systems receive updates from their respective vendors to remediate the buffer overflow condition in the cons_options function. Network-level protections including firewall rules that restrict DHCP traffic to trusted sources and monitoring for anomalous DHCP request patterns can provide additional defense-in-depth measures. The vulnerability aligns with CWE-121 stack-based buffer overflow classification and maps to ATT&CK technique T1059.007 for remote code execution through network services. System administrators should implement regular security audits of network infrastructure components and maintain updated vulnerability assessments to identify similar buffer overflow conditions in other network services. The incident highlights the critical importance of proper input validation and bounds checking in network daemon implementations, particularly those handling untrusted user input from remote sources.