CVE-2018-4255 in macOS
Summary
by MITRE
In macOS High Sierra before 10.13.5, an out-of-bounds read was addressed with improved input validation.
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Analysis
by VulDB Data Team • 04/29/2020
The vulnerability identified as CVE-2018-4255 represents a critical out-of-bounds read flaw discovered in macOS High Sierra versions prior to 10.13.5. This issue resides within the operating system's kernel components and specifically affects the handling of user-supplied input data. The vulnerability manifests when the system processes certain input parameters without adequate validation, potentially allowing malicious actors to access memory locations beyond the intended boundaries. Such out-of-bounds read conditions typically arise from insufficient bounds checking mechanisms that should prevent memory access violations. The flaw falls under the Common Weakness Enumeration category CWE-129, which specifically addresses insufficient validation of length of input buffers, and more broadly relates to CWE-125, which covers out-of-bounds read vulnerabilities. These weaknesses create opportunities for attackers to potentially extract sensitive information from system memory or cause system instability through carefully crafted input sequences.
The operational impact of this vulnerability extends beyond simple memory access issues, as it can enable attackers to gather confidential data from kernel memory spaces. When an out-of-bounds read occurs in kernel space, it may expose sensitive information such as cryptographic keys, user credentials, or system configuration details that are stored in adjacent memory locations. The vulnerability's exploitation potential increases significantly when considering that macOS High Sierra systems were widely deployed in enterprise environments, making them attractive targets for sophisticated adversaries. Attackers could leverage this flaw to gain insights into system internals, potentially leading to privilege escalation or further exploitation of other vulnerabilities present in the operating system. The issue demonstrates a fundamental flaw in input validation practices within the system's kernel components, where proper bounds checking mechanisms were either absent or insufficient to prevent unauthorized memory access patterns.
Security professionals should recognize that this vulnerability aligns with tactics described in the MITRE ATT&CK framework under the privilege escalation and defense evasion categories. The out-of-bounds read can serve as a foundational exploit for more advanced attack vectors, particularly when combined with other vulnerabilities or when attackers can manipulate system memory through crafted inputs. Organizations running affected macOS versions face significant risk exposure, as the vulnerability can be exploited remotely or through local user interactions depending on the specific implementation details. The patch released with macOS 10.13.5 addresses this issue through enhanced input validation mechanisms that properly bounds check all user-supplied data before processing. System administrators should prioritize immediate deployment of the security update to mitigate potential exploitation attempts. Additionally, monitoring for unusual memory access patterns or system behavior that might indicate exploitation attempts can serve as an additional defensive measure. The vulnerability highlights the importance of robust input validation practices in operating system development and underscores the necessity of thorough security testing of kernel components before public release.