CVE-2017-10869 in H2O
Summary
by MITRE
Buffer overflow in H2O version 2.2.2 and earlier allows remote attackers to cause a denial-of-service in the server via unspecified vectors.
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Analysis
by VulDB Data Team • 01/18/2023
The vulnerability identified as CVE-2017-10869 represents a critical buffer overflow condition within the H2O web server software version 2.2.2 and earlier releases. This flaw exists in the server's handling of incoming network requests and can be exploited by remote attackers to execute malicious code or cause system instability. The buffer overflow occurs when the software processes certain input data without proper bounds checking, allowing an attacker to overwrite adjacent memory locations with malicious data. Such vulnerabilities are particularly dangerous because they can be triggered remotely without requiring authentication or prior access to the system. The unspecified vectors mentioned in the description suggest that multiple attack paths could potentially exploit this vulnerability, making it more challenging to defend against and remediate completely. This type of vulnerability directly impacts the integrity and availability of web services hosted on affected H2O servers, creating potential for widespread disruption across multiple organizations that rely on this software stack.
The technical implementation of this buffer overflow vulnerability stems from inadequate input validation mechanisms within the H2O server's core processing modules. When the server receives malformed or excessively large data payloads, the memory allocation routines fail to properly verify the boundaries of the allocated buffers before writing data into memory. This condition creates a situation where attacker-controlled data can overwrite critical program variables, return addresses, or other memory segments essential for proper program execution. According to the CWE (Common Weakness Enumeration) framework, this vulnerability maps to CWE-121, which describes stack-based buffer overflow conditions, and potentially CWE-122 for heap-based buffer overflows depending on the specific implementation details. The attack surface is broadened by the fact that H2O is designed to handle various types of HTTP requests and protocols, increasing the number of potential entry points for exploitation. The vulnerability's remote nature means that attackers can leverage this flaw from anywhere on the internet without requiring physical access or insider knowledge of the target system's internal structure.
The operational impact of CVE-2017-10869 extends beyond simple denial-of-service conditions to potentially enable more sophisticated attacks that could compromise entire server environments. When exploited successfully, this buffer overflow can cause the H2O server process to crash and restart repeatedly, leading to service disruption and potential data loss. More critically, if attackers can control the memory overwrite behavior, they may be able to inject and execute arbitrary code on the affected system, potentially elevating their privileges and gaining full control over the server. The vulnerability affects organizations running H2O versions prior to 2.2.3, which represents a significant portion of web server deployments that were in use during 2017. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1059 (Command and Scripting Interpreter) and T1499 (Endpoint Denial of Service) as attackers can leverage the buffer overflow to execute commands or disrupt services. The widespread adoption of H2O as a lightweight, high-performance web server makes this vulnerability particularly concerning for organizations operating in cloud environments or those managing multiple web applications that depend on this software stack.
Organizations affected by CVE-2017-10869 should prioritize immediate remediation through software updates to version 2.2.3 or later, which contain patches addressing the buffer overflow conditions. The patch implementation requires careful testing to ensure compatibility with existing web applications and configurations, as updates may introduce breaking changes in certain deployment scenarios. System administrators should conduct thorough vulnerability assessments to identify all instances of affected H2O versions across their infrastructure and implement network segmentation to limit potential attack vectors. Additional mitigations include implementing intrusion detection systems that can identify anomalous traffic patterns associated with buffer overflow exploitation attempts, configuring firewalls to restrict unnecessary HTTP traffic, and establishing robust monitoring protocols to detect service disruptions or unusual memory usage patterns. The vulnerability also highlights the importance of regular security updates and patch management processes, as organizations should maintain automated systems for detecting and deploying security patches across their entire infrastructure. Organizations should also consider implementing application-level protections such as address space layout randomization and stack canaries to provide additional defense-in-depth measures against similar buffer overflow vulnerabilities that may exist in other components of their web server stack.