CVE-2017-7167 in Xcode
Summary
by MITRE
An issue was discovered in certain Apple products. Xcode before 9.2 is affected. The issue involves the "ld64" component. A buffer overflow allows remote attackers to execute arbitrary code via crafted source code.
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Analysis
by VulDB Data Team • 01/20/2020
The vulnerability identified as CVE-2017-7167 represents a critical buffer overflow flaw within Apple's Xcode development environment, specifically affecting versions prior to 9.2. This security weakness resides within the ld64 linker component, which serves as a fundamental element in the compilation and linking process of software applications for Apple platforms. The ld64 linker is responsible for combining object files into executable binaries and is an essential part of the Xcode toolchain that developers rely upon for creating applications for iOS, macOS, watchOS, and tvOS. The flaw manifests when the linker processes maliciously crafted source code that triggers a buffer overflow condition in its memory handling mechanisms.
The technical nature of this vulnerability stems from inadequate input validation and memory management within the ld64 component's code processing routines. When Xcode encounters source code containing specially crafted buffer overflow payloads, the linker fails to properly bounds-check memory allocations, allowing attackers to overwrite adjacent memory locations. This memory corruption enables remote attackers to inject and execute arbitrary code with the privileges of the user running the Xcode development environment. The vulnerability operates at the compilation level, meaning that an attacker could potentially compromise a developer's system simply by providing malicious source code that gets compiled through the affected Xcode version. This creates a particularly dangerous attack vector since developers often compile code from untrusted sources during routine development activities, making the attack surface significantly broader than typical software vulnerabilities.
The operational impact of CVE-2017-7167 extends beyond individual developer machines to potentially compromise entire development ecosystems and supply chain integrity. Attackers could exploit this vulnerability by distributing malicious source code packages that appear legitimate to developers, leading to the unintentional compilation of malicious binaries. This scenario creates a sophisticated attack method where the vulnerability can be leveraged to compromise not only the development environment but potentially also the applications being developed, especially if those applications are later deployed to production environments. The vulnerability's remote exploit capability means that attackers need not have physical access to the development systems, making it particularly concerning for organizations that maintain distributed development teams or rely on third-party code contributions. The potential for code execution at the compilation stage also means that attackers could potentially modify legitimate applications during the build process, creating backdoors or other malicious functionality that persists in the compiled applications.
This vulnerability aligns with CWE-121, which describes buffer overflow conditions where insufficient bounds checking allows memory corruption, and can be categorized under ATT&CK technique T1059.001 for command and scripting interpreter usage. The attack pattern follows the typical methodology of supply chain compromise where attackers target development tools rather than end-user applications, creating a more pervasive threat vector. Organizations should implement comprehensive security measures including regular Xcode updates, code review processes, and development environment hardening to mitigate the risk of exploitation. The vulnerability underscores the importance of maintaining secure development practices and highlights the critical need for developers to keep their toolchains updated to prevent exploitation of such fundamental infrastructure vulnerabilities. Security teams should also consider implementing automated scanning solutions that can detect potentially malicious code patterns during the development process, providing an additional layer of protection against such sophisticated attacks.