CVE-2007-5029 in Dibbler
Summary
by MITRE
Dibbler 0.6.0 does not verify that certain length parameters are appropriate for buffer sizes, which allows remote attackers to trigger a buffer over-read and cause a denial of service (daemon crash), as demonstrated by incorrect behavior of the TSrvMsg constructor in SrvMessages/SrvMsg.cpp when (1) reading the option code and option length and (2) parsing options.
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Analysis
by VulDB Data Team • 07/29/2021
The vulnerability identified as CVE-2007-5029 affects Dibbler version 0.6.0, a DHCPv6 client and server implementation that operates within IPv6 network environments. This security flaw resides in the server component's message handling mechanism, specifically within the TSrvMsg constructor located in the SrvMessages/SrvMsg.cpp file. The issue represents a classic buffer over-read condition that occurs when the software fails to properly validate length parameters against available buffer sizes during the processing of DHCPv6 messages.
The technical flaw manifests when the TSrvMsg constructor processes incoming DHCPv6 messages containing malformed option codes and lengths. During the parsing phase, the software reads option codes and their corresponding lengths without adequate validation to ensure these values remain within acceptable buffer boundaries. This insufficient validation creates an opportunity for remote attackers to craft specially crafted DHCPv6 packets that contain oversized or malformed option parameters. When the server attempts to process these malformed options, the lack of proper bounds checking leads to memory access violations that result in daemon crashes and subsequent denial of service conditions.
The operational impact of this vulnerability extends beyond simple service disruption as it can be exploited remotely without authentication requirements, making it particularly dangerous in network environments where DHCPv6 servers are exposed to untrusted networks. Attackers can leverage this vulnerability to repeatedly crash the Dibbler server daemon, effectively rendering the DHCPv6 service unavailable to legitimate network clients. The vulnerability specifically targets the server-side implementation and affects any system running Dibbler 0.6.0 where the daemon is actively processing DHCPv6 messages from clients.
From a cybersecurity perspective, this vulnerability aligns with CWE-129, which describes improper validation of length parameters, and represents a form of buffer over-read that can be classified under the ATT&CK technique T1499.3 for network denial of service. The weakness creates an entry point for attackers to perform service disruption attacks that can impact network connectivity and availability. Organizations using Dibbler 0.6.0 should consider this vulnerability as a critical threat requiring immediate attention, particularly in environments where network infrastructure reliability is paramount.
Mitigation strategies should include immediate upgrading to a patched version of Dibbler that properly validates option length parameters against buffer boundaries. System administrators should also implement network segmentation to limit exposure of DHCPv6 servers to untrusted networks and consider deploying intrusion detection systems to monitor for anomalous DHCPv6 traffic patterns. Additionally, regular security assessments should verify that all DHCPv6 implementations properly validate input parameters and maintain appropriate bounds checking mechanisms to prevent similar buffer over-read conditions from occurring in other network services.