CVE-2017-5209 in libplist
Summary
by MITRE
The base64decode function in base64.c in libimobiledevice libplist through 1.12 allows attackers to obtain sensitive information from process memory or cause a denial of service (buffer over-read) via split encoded Apple Property List data.
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Analysis
by VulDB Data Team • 10/28/2022
The vulnerability identified as CVE-2017-5209 affects the libimobiledevice libplist library version 1.12 and earlier, specifically within the base64decode function located in base64.c. This issue arises from improper handling of split encoded Apple Property List data during base64 decoding operations. The flaw manifests when the library processes base64 encoded data that has been fragmented or split across multiple segments, leading to memory corruption vulnerabilities that can be exploited by malicious actors.
The technical implementation of this vulnerability stems from a buffer over-read condition that occurs when the base64decode function fails to properly validate the boundaries of input data. When processing split encoded data, the function does not adequately check the length of the input buffer or the expected output size, allowing an attacker to manipulate the decoding process to read beyond allocated memory boundaries. This behavior creates a predictable pattern where attacker-controlled data can cause the function to access memory locations that contain sensitive information or cause the application to crash due to invalid memory access. The vulnerability operates at the protocol level within the mobile device communication stack, specifically affecting the property list parsing functionality that is fundamental to iOS device communication protocols.
From an operational impact perspective, this vulnerability presents significant security risks to systems that rely on libimobiledevice for mobile device management or forensic analysis operations. An attacker could potentially exploit this flaw to extract sensitive information from process memory, including cryptographic keys, authentication tokens, or other confidential data that might be stored in memory during the decoding process. The denial of service aspect of this vulnerability means that legitimate applications using the library could be disrupted, causing service interruptions for mobile device management systems, forensic tools, or development environments that depend on proper property list parsing. The attack surface extends to any application that interfaces with iOS devices through the libimobiledevice library, including enterprise mobile device management platforms, security research tools, and forensic analysis software.
The mitigation strategies for CVE-2017-5209 primarily involve upgrading to libplist version 1.13 or later, where the buffer over-read condition has been addressed through proper input validation and boundary checking mechanisms. Organizations should also implement defensive programming practices such as validating input data lengths before processing, using safe string manipulation functions, and employing memory protection mechanisms like stack canaries or address space layout randomization. Additionally, network segmentation and access controls should be implemented to limit exposure of systems that use the vulnerable library, particularly in enterprise environments where mobile device management is critical. This vulnerability aligns with CWE-129, which addresses improper validation of length of input buffers, and may map to ATT&CK technique T1059.007 for command and scripting interpreter usage in exploitation contexts. Security teams should monitor for potential exploitation attempts and implement intrusion detection systems that can identify anomalous base64 decoding patterns that might indicate attempts to trigger this vulnerability.