CVE-2018-20374 in Tiny C Compiler
Summary
by MITRE
An issue was discovered in Tiny C Compiler (aka TinyCC or TCC) 0.9.27. Compiling a crafted source file leads to an 8 byte out of bounds write in the use_section1 function in tccasm.c.
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Analysis
by VulDB Data Team • 04/23/2020
The vulnerability identified as CVE-2018-20374 represents a critical memory corruption flaw in Tiny C Compiler version 0.9.27, a lightweight compiler designed for rapid compilation and execution of C code. This issue manifests as an 8-byte out-of-bounds write condition that occurs during the compilation process when processing specifically crafted source files, making it a significant concern for developers and system administrators who rely on this compiler for code compilation tasks.
The technical flaw resides within the use_section1 function located in the tccasm.c source file of the TinyCC codebase. This function handles section management during assembly processing, where improper bounds checking allows an attacker to write 8 bytes of data beyond the allocated memory buffer. The vulnerability stems from insufficient input validation and memory boundary verification during the compilation phase, particularly when dealing with malformed or malicious assembly directives. The flaw operates at the compiler level rather than the runtime environment, meaning that successful exploitation requires an attacker to convince a victim to compile a malicious source file through the vulnerable compiler.
The operational impact of this vulnerability extends beyond simple memory corruption, as it creates potential pathways for arbitrary code execution and system compromise. An attacker could leverage this out-of-bounds write to overwrite critical memory locations, potentially leading to privilege escalation, denial of service conditions, or even remote code execution depending on the execution context. The vulnerability affects any system where TinyCC is installed and used for compiling source code, including development environments, automated build systems, and embedded platforms that utilize this lightweight compiler. Given the widespread use of TinyCC in various development scenarios and embedded systems, the potential attack surface is substantial.
Mitigation strategies for CVE-2018-20374 should focus on immediate patching of the TinyCC compiler to version 0.9.28 or later, which contains the necessary fixes for the memory bounds checking issue. System administrators should also implement strict source code validation procedures and avoid compiling untrusted code through the compiler. Additional protective measures include deploying runtime application control mechanisms, implementing sandboxing techniques for compilation processes, and monitoring for suspicious compilation activities. This vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and may be categorized under ATT&CK technique T1059.007 for execution through compiler-based attacks, highlighting the need for comprehensive security measures in compilation environments. Organizations should also consider implementing automated code review processes that can detect potentially malicious patterns in source code before compilation occurs.