CVE-2018-18481 in libopencad
Summary
by MITRE
A heap-based buffer over-read exists in libopencad 0.2.0 in the ReadCHAR function in lib/dwg/io.cpp, resulting in an application crash.
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Analysis
by VulDB Data Team • 05/30/2023
The vulnerability identified as CVE-2018-18481 represents a critical heap-based buffer over-read flaw within the libopencad library version 0.2.0. This issue specifically manifests within the ReadCHAR function located in the lib/dwg/io.cpp file, demonstrating a classic memory safety vulnerability that can severely impact software stability and security. The flaw occurs when the application attempts to read data from a memory buffer that has been allocated on the heap, but the read operation extends beyond the allocated memory boundaries. Such over-read conditions typically arise from improper bounds checking or incorrect calculation of buffer sizes during data processing operations, creating a scenario where the program accesses memory locations that may contain sensitive information or cause unpredictable behavior.
The technical implementation of this vulnerability stems from inadequate input validation within the ReadCHAR function, which processes character data during CAD file parsing operations. When malformed or excessively large character data is encountered, the function fails to properly verify buffer boundaries before performing memory read operations. This flaw falls under the Common Weakness Enumeration category CWE-125, which specifically addresses out-of-bounds read vulnerabilities, and aligns with the broader class of heap-based buffer overflows that represent significant security risks. The vulnerability's impact is particularly concerning given that libopencad is a library designed for computer-aided design file processing, where such flaws could be exploited through malicious CAD files or manipulated data inputs. The heap-based nature of the over-read indicates that the vulnerable memory allocation occurs dynamically during program execution, making the exploitation potential more sophisticated and harder to predict compared to stack-based buffer overflows.
From an operational standpoint, this vulnerability creates substantial risk for applications that depend on libopencad for CAD file processing, potentially leading to application crashes, denial of service conditions, or in more severe scenarios, arbitrary code execution. The buffer over-read could expose sensitive memory contents to unauthorized access, particularly if the heap memory contains other program data or credentials. Attackers could potentially leverage this vulnerability by crafting malicious CAD files that trigger the vulnerable ReadCHAR function, causing the target application to crash or behave unpredictably. The exploitation pathway aligns with ATT&CK technique T1059.007 for application execution and T1499.004 for network denial of service, depending on the specific attack scenario. Organizations using libopencad in their CAD workflows, design automation systems, or engineering applications face significant operational risks, as the vulnerability could disrupt critical design processes and potentially provide attackers with opportunities to escalate privileges or gain unauthorized access to sensitive design data.
The mitigation strategy for CVE-2018-18481 requires immediate patching of the libopencad library to version 0.2.1 or later, which includes the necessary bounds checking fixes for the ReadCHAR function. System administrators and developers should implement input validation measures that enforce strict buffer size limits and sanitize all CAD file inputs before processing. Additionally, deploying memory safety tools such as address sanitizers, heap profilers, and static analysis tools can help detect similar vulnerabilities in other components of the software ecosystem. The fix should incorporate proper bounds checking mechanisms that verify character data lengths against allocated buffer sizes, ensuring that no memory read operations exceed the intended buffer boundaries. Organizations should also consider implementing network segmentation and access controls for systems processing CAD files, along with regular security assessments to identify and remediate similar vulnerabilities across their software infrastructure. The remediation process must include comprehensive testing to ensure that the patched version maintains full compatibility with existing CAD file processing workflows while eliminating the buffer over-read condition that could lead to system instability or security breaches.