CVE-2017-7136 in Xcode
Summary
by MITRE
An issue was discovered in certain Apple products. Xcode before 9 is affected. The issue involves the "ld64" component. It allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) via a crafted Mach-O file.
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Analysis
by VulDB Data Team • 01/14/2021
The vulnerability identified as CVE-2017-7136 represents a critical security flaw in Apple's Xcode development environment that affected versions prior to Xcode 9. This issue specifically targets the ld64 linker component, which is responsible for linking object files into executable binaries during the software compilation process. The vulnerability arises from insufficient input validation within the Mach-O file parser, creating a pathway for malicious actors to exploit the system through specially crafted binary files.
The technical flaw manifests as a memory corruption vulnerability within the ld64 linker when processing malformed Mach-O files. This memory corruption occurs during the parsing and linking phases of software compilation, where the linker fails to properly validate the structure and content of input files before attempting to process them. The vulnerability is classified as a buffer overflow or memory corruption issue that can be triggered by feeding maliciously constructed Mach-O files to the compiler. This type of vulnerability falls under the CWE-121 category of Buffer Overflow, specifically involving heap-based buffer overflows that can lead to arbitrary code execution.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it provides remote attackers with the capability to execute arbitrary code on systems running affected versions of Xcode. This means that any developer using Xcode before version 9 could potentially be compromised simply by opening or processing a malicious Mach-O file within their development environment. The vulnerability is particularly dangerous because it operates at the compilation stage, where developers often trust the tools they are using to build their applications. Attackers could craft malicious libraries or frameworks that appear legitimate but contain malicious code that gets executed during the linking process, potentially compromising the entire development environment.
The attack surface for this vulnerability is significant given that Xcode is widely used across the iOS, macOS, and tvOS development ecosystem. Developers who unknowingly incorporate malicious components into their projects could inadvertently introduce backdoors or malware into their applications, creating a supply chain attack vector. The vulnerability also enables denial of service attacks that could disrupt development workflows and potentially cause application crashes. From an adversary perspective, this vulnerability aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter, as it allows for code execution through legitimate development tools. The compromise of development environments through such vulnerabilities represents a sophisticated attack vector that can affect not just individual developers but entire organizations and their software products.
Mitigation strategies for CVE-2017-7136 primarily focus on updating to Xcode 9 or later versions where the ld64 linker has been patched to properly validate Mach-O file structures. Organizations should implement strict code review processes and source verification procedures to prevent the inclusion of untrusted components in development projects. Additionally, security awareness training for developers should emphasize the importance of verifying the integrity of third-party libraries and frameworks before incorporating them into applications. System administrators should monitor for any suspicious activity related to development environments and consider implementing network segmentation to limit potential attack vectors. The vulnerability also underscores the importance of maintaining up-to-date development tools and following secure coding practices throughout the software development lifecycle to prevent similar issues from arising in the future.