CVE-2015-5177 in ESXi
Summary
by MITRE
Double free vulnerability in the SLPDKnownDAAdd function in slpd/slpd_knownda.c in OpenSLP 1.2.1 allows remote attackers to cause a denial of service (crash) via a crafted package.
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Analysis
by VulDB Data Team • 06/20/2022
The CVE-2015-5177 vulnerability represents a critical double free error within the OpenSLP 1.2.1 implementation that exposes systems to remote denial of service attacks. This flaw exists within the SLPDKnownDAAdd function located in the slpd/slpd_knownda.c source file, making it a fundamental issue in the service location protocol daemon's handling of known directory agents. The vulnerability arises from improper memory management practices where the same memory block gets freed twice during the processing of a specially crafted SLP packet, creating a condition that can be exploited by remote attackers to crash the slpd service.
The technical execution of this vulnerability leverages the inherent design of the SLP protocol's directory agent management system where the SLPDKnownDAAdd function processes incoming directory agent advertisements. When a malformed packet is received, the function fails to properly validate the packet structure before attempting memory deallocation operations, leading to the double free condition. This memory corruption scenario occurs because the function does not adequately check if a memory block has already been freed before attempting to free it again, a classic memory safety issue that falls under the CWE-415 vulnerability category. The flaw demonstrates poor defensive programming practices where input validation and memory state tracking are insufficient to prevent the execution path that leads to the double free condition.
From an operational impact perspective, this vulnerability presents a significant threat to systems relying on OpenSLP for service discovery and network directory services. The remote exploitation capability means that any system running the vulnerable slpd daemon is potentially accessible to attackers who can craft malicious SLP packets to trigger the crash. This creates a denial of service condition that can disrupt network services, particularly in environments where SLP is used for critical infrastructure discovery, such as enterprise networks, IoT deployments, or any system architecture that depends on service location protocols. The vulnerability's exploitation does not require authentication, making it particularly dangerous in network environments where SLP traffic is not properly restricted or filtered. The impact extends beyond simple service disruption to potentially affect network stability and availability of services that depend on proper directory agent functionality.
The remediation approach for CVE-2015-5177 requires immediate patching of the OpenSLP 1.2.1 implementation to address the memory management flaw in the SLPDKnownDAAdd function. This involves implementing proper input validation and memory state tracking to prevent the double free condition from occurring. Organizations should also consider implementing network segmentation and firewall rules to restrict SLP traffic where possible, particularly in environments where the service is not actively required. The vulnerability's classification under ATT&CK technique T1499.004 for network denial of service provides additional context for defensive measures, as this represents a classic exploitation pattern that can be detected through network monitoring and anomaly detection systems. Security teams should also implement regular vulnerability assessments targeting service location protocols and ensure that all network services are kept up to date with the latest security patches to prevent similar memory safety issues from compromising system availability.