CVE-2018-20004 in Mini-XML
Summary
by MITRE
An issue has been found in Mini-XML (aka mxml) 2.12. It is a stack-based buffer overflow in mxml_write_node in mxml-file.c via vectors involving a double-precision floating point number and the '<order type="real">' substring, as demonstrated by testmxml.
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Analysis
by VulDB Data Team • 06/13/2023
The vulnerability identified as CVE-2018-20004 represents a critical stack-based buffer overflow within the Mini-XML library version 2.12, specifically affecting the mxml_write_node function in the mxml-file.c source file. This flaw arises from improper handling of double-precision floating point numbers when processing XML nodes with the specific substring pattern '<order type="real">', which creates a dangerous condition where attacker-controlled data can overwrite adjacent stack memory. The vulnerability demonstrates how seemingly innocuous XML parsing operations can become vectors for arbitrary code execution when input validation is insufficient.
The technical implementation of this vulnerability stems from a classic buffer overflow scenario where the mxml_write_node function fails to properly validate the length of data being written to a stack-allocated buffer. When processing XML elements containing the '<order type="real">' pattern, the library attempts to serialize floating point values without adequate bounds checking, allowing malicious input to exceed the allocated buffer space. This behavior directly aligns with CWE-121 Stack-based Buffer Overflow, which describes buffer overflow conditions where insufficient bounds checking allows data to overwrite adjacent memory locations on the stack. The vulnerability is particularly dangerous because it can be triggered through standard XML parsing operations, making it exploitable in applications that process untrusted XML input.
The operational impact of CVE-2018-20004 extends beyond simple denial of service scenarios, as it creates potential for remote code execution in vulnerable applications. When exploited, this buffer overflow could allow attackers to overwrite return addresses, function pointers, or other critical stack data, potentially enabling arbitrary code execution with the privileges of the affected application. The vulnerability affects any software utilizing Mini-XML 2.12 for XML processing, including web applications, network services, and embedded systems that parse XML data from untrusted sources. This makes it particularly concerning for applications in the ATT&CK framework's initial access and execution phases, where adversaries might leverage such vulnerabilities to establish persistent access to target systems.
Mitigation strategies for CVE-2018-20004 should prioritize immediate patching of affected Mini-XML library versions, with the release of version 2.13 addressing this specific buffer overflow condition. Organizations should implement input validation measures to sanitize XML data before processing, particularly focusing on XML elements that might trigger the vulnerable code path. Additionally, deployment of address space layout randomization, stack canaries, and other exploit mitigations can reduce the effectiveness of potential exploitation attempts. System administrators should also consider implementing network segmentation and access controls to limit exposure of applications that process untrusted XML input, while monitoring for anomalous XML parsing activities that might indicate exploitation attempts. The vulnerability serves as a reminder of the importance of thorough input validation and bounds checking in XML processing libraries, particularly when handling numeric data types that require careful serialization to prevent memory corruption scenarios.