CVE-2017-6438 in libplist
Summary
by MITRE
Heap-based buffer overflow in the parse_unicode_node function in bplist.c in libimobiledevice libplist 1.12 allows local users to cause a denial of service (out-of-bounds write) and possibly code execution via a crafted plist file.
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Analysis
by VulDB Data Team • 09/09/2020
The vulnerability identified as CVE-2017-6438 represents a critical heap-based buffer overflow within the libimobiledevice libplist library version 1.12. This flaw exists in the parse_unicode_node function located in the bplist.c file, which is part of a widely used library for parsing and manipulating property list files on iOS devices and other platforms. The library serves as a foundational component for various mobile device management tools and forensic analysis software, making this vulnerability particularly concerning from a security perspective.
The technical implementation of this vulnerability stems from inadequate bounds checking within the parse_unicode_node function when processing unicode character sequences in binary plist files. When a maliciously crafted plist file is processed, the function fails to properly validate the length of unicode data before writing to allocated heap memory, resulting in an out-of-bounds write condition. This memory corruption scenario can be exploited by attackers who craft specially formatted plist files containing malformed unicode sequences that exceed the expected buffer boundaries. The vulnerability manifests as a heap-based buffer overflow, where the program writes data beyond the allocated memory region, potentially overwriting adjacent memory structures and compromising the stability of the application.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable remote code execution in certain scenarios. Local attackers who can convince a victim to process a crafted plist file through an application using libplist will be able to trigger the buffer overflow, leading to application crashes and system instability. More critically, the out-of-bounds write condition creates opportunities for attackers to manipulate memory layout and potentially execute arbitrary code, particularly when the vulnerable application processes untrusted plist data from external sources. The vulnerability affects systems where libplist is integrated, including mobile device management platforms, forensic analysis tools, and iOS development environments that rely on this library for property list processing.
Mitigation strategies for CVE-2017-6438 should prioritize immediate patching of affected libplist library versions, with the recommended approach being the upgrade to version 2.0.0 or later where the buffer overflow has been addressed through proper bounds checking mechanisms. Organizations should implement strict input validation procedures for all property list files processed by applications utilizing libplist, including sanitizing and validating plist content before parsing operations. System administrators should also consider implementing application sandboxing and privilege separation techniques to limit the potential impact of successful exploitation attempts. The vulnerability aligns with CWE-121 heap-based buffer overflow classification and represents a significant concern under the ATT&CK framework's execution and privilege escalation tactics, particularly when considering that the affected library is commonly used in mobile device management and forensic analysis contexts where attackers may seek to leverage such vulnerabilities for unauthorized access to iOS devices and their associated data.