CVE-2017-13811 in macOS
Summary
by MITRE
An issue was discovered in certain Apple products. macOS before 10.13.1 is affected. The issue involves the "fsck_msdos" component. It allows attackers to execute arbitrary code in a privileged context or cause a denial of service (memory corruption) via a crafted app.
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Analysis
by VulDB Data Team • 09/04/2024
The vulnerability identified as CVE-2017-13811 represents a critical security flaw within Apple's macOS operating system affecting versions prior to 10.13.1. This issue specifically targets the fsck_msdos component, which is responsible for checking and repairing filesystems formatted with the Microsoft DOS filesystem format. The flaw exists in how the system handles certain malformed or crafted input data during filesystem validation processes, creating a pathway for malicious actors to exploit the system's privilege escalation mechanisms. The vulnerability falls under the category of memory corruption issues that can be leveraged to execute arbitrary code with elevated privileges, making it particularly dangerous for system security.
The technical implementation of this vulnerability stems from insufficient input validation within the fsck_msdos utility, which is part of the core system utilities that manage filesystem integrity checks. When the system processes a specially crafted application or filesystem image, the utility fails to properly sanitize the input data, leading to buffer overflows or other memory corruption conditions. This allows attackers to manipulate the execution flow of the privileged utility and inject malicious code that executes with root-level privileges. The flaw demonstrates characteristics consistent with CWE-121, which describes heap-based buffer overflow conditions, and potentially CWE-787, representing out-of-bounds write vulnerabilities that can lead to arbitrary code execution in privileged contexts.
From an operational impact perspective, this vulnerability enables attackers to gain unauthorized access to system resources and potentially compromise the entire operating environment. The ability to execute arbitrary code in a privileged context means that an attacker could install malware, modify system files, steal sensitive data, or establish persistent backdoors within the affected system. The denial of service component of this vulnerability adds additional risk as attackers could also cause system instability or complete crashes through carefully crafted inputs that trigger memory corruption. This represents a significant threat to enterprise environments where macOS systems may be running outdated versions, as the attack surface remains exposed for extended periods without proper patch management.
Security professionals should implement immediate mitigation strategies including mandatory system updates to macOS 10.13.1 or later versions where this vulnerability has been addressed through proper input validation and memory management improvements. Organizations should also consider implementing network monitoring solutions to detect potential exploitation attempts and maintain robust patch management policies to ensure all systems remain current with security updates. The vulnerability aligns with tactics described in the ATT&CK framework under privilege escalation and execution techniques, specifically targeting the use of system utilities to gain elevated privileges. Additional defensive measures include restricting user access to filesystem utilities and implementing application whitelisting policies to prevent unauthorized execution of potentially malicious applications that could exploit this flaw.