CVE-2018-20353 in Mongoose Embedded Web Server Library
Summary
by MITRE
An invalid read of 8 bytes due to a use-after-free vulnerability during a "NULL test" in the mg_http_get_proto_data function in mongoose.c in Cesanta Mongoose Embedded Web Server Library 6.13 and earlier allows a denial of service (application crash) or remote code execution.
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Analysis
by VulDB Data Team • 10/03/2023
The vulnerability identified as CVE-2018-20353 represents a critical use-after-free condition within the Cesanta Mongoose Embedded Web Server Library version 6.13 and earlier. This flaw manifests during the execution of the mg_http_get_proto_data function where a null test operation triggers an invalid read of 8 bytes, creating a dangerous memory access pattern that can be exploited by malicious actors. The issue stems from improper memory management practices where freed memory locations are accessed after the original allocation has been released, leading to unpredictable behavior and potential system compromise.
The technical implementation of this vulnerability involves a specific code path within the mongoose.c file where the mg_http_get_proto_data function performs a null test on a pointer that may have already been freed. When the application attempts to read 8 bytes from this freed memory location, it triggers a memory access violation that can result in application crash or more severely, provide an attacker with opportunities for remote code execution. This type of vulnerability falls under CWE-416, which specifically addresses use-after-free conditions in software implementations. The memory corruption occurs during HTTP protocol data handling, making it particularly dangerous in web server environments where multiple concurrent connections are processed.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to encompass potential remote code execution capabilities that could allow attackers to gain control over affected systems. When exploited, the vulnerability can cause the embedded web server to crash repeatedly, rendering the service unavailable to legitimate users and potentially providing attackers with a foothold for further exploitation. The embedded nature of the Cesanta Mongoose library means that this vulnerability affects numerous applications and devices that rely on this web server component, including IoT devices, embedded systems, and various network appliances that utilize embedded web interfaces. The vulnerability's classification aligns with ATT&CK technique T1203, which covers exploitation for privilege escalation through memory corruption vulnerabilities.
Mitigation strategies for CVE-2018-20353 require immediate attention from system administrators and developers who utilize the Cesanta Mongoose library. The primary recommendation involves upgrading to version 6.14 or later of the Mongoose Embedded Web Server Library where this vulnerability has been addressed through proper memory management implementation. Organizations should conduct thorough inventory assessments to identify all systems and applications that depend on the vulnerable library version. Additionally, implementing network segmentation and access controls can help limit the potential impact of exploitation attempts. Security monitoring should be enhanced to detect unusual patterns of service disruption or memory access violations that may indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper memory management practices and regular security updates in embedded systems where resource constraints often lead to inadequate security testing and validation of memory handling operations.