CVE-2017-7185 in MongooseOS
Summary
by MITRE
Use-after-free vulnerability in the mg_http_multipart_wait_for_boundary function in mongoose.c in Cesanta Mongoose Embedded Web Server Library 6.7 and earlier and Mongoose OS 1.2 and earlier allows remote attackers to cause a denial of service (crash) via a multipart/form-data POST request without a MIME boundary string.
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Analysis
by VulDB Data Team • 07/13/2024
The CVE-2017-7185 vulnerability represents a critical use-after-free flaw within the Cesanta Mongoose Embedded Web Server Library affecting versions 6.7 and earlier, as well as Mongoose OS 1.2 and earlier. This vulnerability specifically resides in the mg_http_multipart_wait_for_boundary function, which handles multipart/form-data POST requests in web server implementations. The flaw manifests when the web server receives a malformed multipart request that lacks a proper MIME boundary string, creating a dangerous condition where memory previously allocated to handle boundary parsing is accessed after being freed.
The technical nature of this vulnerability stems from improper memory management within the multipart handling logic. When a multipart/form-data request is processed without a valid boundary specification, the mg_http_multipart_wait_for_boundary function fails to properly validate the input before proceeding with memory operations. This allows an attacker to craft a malicious POST request that triggers a sequence where memory chunks are freed but subsequently accessed, leading to undefined behavior. The vulnerability operates at the application layer and can be exploited remotely without authentication, making it particularly dangerous in networked environments.
The operational impact of CVE-2017-7185 translates directly into denial of service conditions that can crash the affected web server instances. Remote attackers can reliably trigger system instability by sending carefully crafted multipart requests that exploit the use-after-free condition, causing the server to terminate unexpectedly. This disruption affects any embedded systems, IoT devices, or web applications that rely on the Cesanta Mongoose library for HTTP handling, potentially leading to service interruptions and availability issues. The vulnerability's remote exploitability means that attackers do not require physical access or local privileges to cause disruption, amplifying its operational impact in production environments.
From a cybersecurity perspective, this vulnerability aligns with CWE-416, which addresses use-after-free conditions in memory management, and demonstrates characteristics consistent with ATT&CK technique T1499.004 for network denial of service attacks. The flaw represents a classic memory safety issue that has been prevalent in embedded systems and lightweight web server implementations where thorough input validation and memory management practices may be insufficient. Organizations utilizing affected versions of the Mongoose library should prioritize immediate patching and consider implementing network-level mitigations such as request filtering and rate limiting to prevent exploitation while awaiting updates. The vulnerability underscores the importance of proper input validation and memory management in embedded systems, particularly those handling network requests in resource-constrained environments where traditional security measures may be limited.