CVE-2018-21027 in Boa
Summary
by MITRE
Boa through 0.94.14rc21 allows remote attackers to trigger an out-of-memory (OOM) condition because malloc is mishandled.
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Analysis
by VulDB Data Team • 01/08/2024
The vulnerability identified as CVE-2018-21027 affects the Boa web server version 0.94.14rc21 and earlier, presenting a critical remote out-of-memory condition that can be exploited by attackers to cause denial of service. This issue stems from improper handling of memory allocation functions within the server's codebase, specifically involving the malloc function which is fundamental to dynamic memory management in C-based applications. The flaw enables remote attackers to craft malicious requests that trigger excessive memory consumption, ultimately leading to system resource exhaustion and service disruption.
The technical root cause of this vulnerability lies in the improper management of memory allocation operations within Boa's request processing pipeline. When the web server receives specially crafted requests, it fails to properly validate or limit memory allocation requests, allowing attackers to consume excessive system resources through repeated or oversized memory allocation calls. This memory mishandling represents a classic example of improper resource management that can be classified under CWE-401, which deals with insufficient resource management and memory leaks. The vulnerability is particularly dangerous because it can be exploited remotely without authentication, making it an attractive target for automated attacks.
The operational impact of CVE-2018-21027 extends beyond simple service disruption to potentially compromise the entire system stability. When exploited successfully, the out-of-memory condition can cause the Boa web server process to terminate unexpectedly, leading to complete service unavailability for legitimate users. Additionally, the memory exhaustion can affect other processes running on the same system, potentially causing cascading failures that impact overall system performance and reliability. This vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and can be categorized under the broader category of resource exhaustion attacks that target system stability rather than direct data compromise.
Mitigation strategies for this vulnerability should focus on immediate patching of the Boa web server to version 0.94.14rc22 or later, which contains the necessary memory management fixes. System administrators should also implement rate limiting and connection throttling mechanisms to prevent abuse of the memory allocation functionality. Network-level protections such as intrusion detection systems can help identify and block malicious requests that attempt to exploit this vulnerability. Additionally, implementing memory monitoring and alerting systems can provide early detection of potential exploitation attempts, allowing for rapid response to prevent service disruption. The fix addresses the underlying malloc handling issue by implementing proper bounds checking and memory allocation limits, ensuring that the web server can gracefully handle unexpected input without exhausting system resources.