CVE-2017-6436 in libplist
Summary
by MITRE
The parse_string_node function in bplist.c in libimobiledevice libplist 1.12 allows local users to cause a denial of service (memory allocation error) via a crafted plist file.
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Analysis
by VulDB Data Team • 09/09/2020
The vulnerability identified as CVE-2017-6436 resides within the libimobiledevice libplist library version 1.12, specifically within the parse_string_node function located in the bplist.c file. This library serves as a critical component for parsing and generating property list files used in Apple's mobile device ecosystem, particularly for communication between desktop applications and iOS devices. The flaw manifests when the library processes maliciously crafted plist files that contain malformed string node data, leading to improper memory allocation behavior that can result in system instability.
The technical implementation of this vulnerability involves the parse_string_node function failing to properly validate input parameters during the parsing of binary plist files. When confronted with a specially constructed plist file containing crafted string data, the function attempts to allocate memory without adequate bounds checking or input sanitization. This memory allocation error occurs because the parser does not properly handle cases where string length values are manipulated to exceed acceptable limits or where the structure of the plist file violates expected formatting conventions. The function's insufficient error handling causes it to proceed with memory allocation requests that either exceed available system resources or create invalid memory states that trigger system crashes or denial of service conditions.
From an operational impact perspective, this vulnerability presents a significant risk to systems that rely on libplist for processing iOS device data, including mobile device management platforms, forensic analysis tools, and development environments that interface with Apple devices. Local attackers can exploit this weakness by creating or obtaining malicious plist files that, when processed by affected applications, will cause the parsing function to fail and consume excessive memory resources or trigger segmentation faults. The denial of service condition affects the availability of services that depend on proper plist parsing, potentially disrupting mobile device provisioning, backup operations, or device synchronization processes that are critical for enterprise environments and mobile device management workflows.
The vulnerability aligns with CWE-129, which addresses improper validation of length values, and CWE-125, which covers out-of-bounds read conditions. From an adversary perspective, this weakness maps to ATT&CK technique T1059.007 for execution through scripting and T1499.004 for denial of service attacks. The attack surface is particularly relevant for security professionals managing mobile device environments, as the vulnerability can be exploited through seemingly benign plist files that appear legitimate but contain hidden malicious structures. Organizations should implement immediate mitigations including updating to libplist versions that address this memory allocation flaw, implementing input validation for plist files processed by affected systems, and deploying sandboxing mechanisms to isolate plist parsing operations. Additionally, security monitoring should be enhanced to detect unusual memory allocation patterns or process crashes that may indicate exploitation attempts. The vulnerability underscores the importance of proper input validation in parsing libraries and demonstrates how seemingly minor flaws in data processing functions can create significant availability risks in mobile device management infrastructure.