CVE-2017-9831 in libmtp
Summary
by MITRE
An integer overflow vulnerability in the ptp_unpack_EOS_CustomFuncEx function of the ptp-pack.c file of libmtp (version 1.1.12 and below) allows attackers to cause a denial of service (out-of-bounds memory access) or maybe remote code execution by inserting a mobile device into a personal computer through a USB cable.
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Analysis
by VulDB Data Team • 12/09/2022
The integer overflow vulnerability identified as CVE-2017-9831 resides within the libmtp library's ptp-pack.c file, specifically in the ptp_unpack_EOS_CustomFuncEx function. This flaw affects versions 1.1.12 and earlier of the libmtp library, which is widely used for managing media transfer protocol devices including digital cameras, smartphones, and other multimedia devices. The vulnerability manifests when a maliciously crafted mobile device is connected to a computer via USB cable, triggering the library's processing of device-specific custom function data. The issue stems from inadequate input validation and integer overflow handling during the parsing of device configuration parameters, creating a scenario where attacker-controlled data can manipulate memory access patterns beyond intended boundaries.
The technical exploitation of this vulnerability occurs through a specific code path where the ptp_unpack_EOS_CustomFuncEx function processes custom function data from EOS (Canon) devices without proper bounds checking on integer values. When a device with maliciously constructed data is connected, the function attempts to unpack and process custom function parameters that exceed the expected integer range, leading to integer overflow conditions. This overflow can cause memory allocation calculations to wrap around to extremely small values or negative numbers, resulting in out-of-bounds memory access patterns. The vulnerability aligns with CWE-190, Integer Overflow or Wraparound, and represents a classic example of how improper integer handling in protocol parsing can lead to memory corruption issues. The ATT&CK framework categorizes this under T1059.007 for Command and Scripting Interpreter: Python, as the vulnerability affects systems where libmtp is used for device management and can be exploited through automated device connection scenarios.
The operational impact of CVE-2017-9831 extends beyond simple denial of service to potentially enabling remote code execution in certain environments. While the primary effect is denial of service through out-of-bounds memory access causing application crashes or system instability, the integer overflow condition creates opportunities for more severe exploitation. When the overflow occurs during memory allocation calculations, it can lead to heap corruption that might be leveraged for arbitrary code execution if the system is running with sufficient privileges. The vulnerability is particularly concerning in automated environments where devices connect and disconnect frequently, as attackers can repeatedly trigger the overflow condition to destabilize systems or potentially gain control. This makes the vulnerability particularly dangerous in enterprise environments where automated device management systems are prevalent and where attackers might leverage the condition through physical access or social engineering to connect malicious devices. The impact is amplified because the vulnerability requires no special privileges to trigger, as it occurs during normal device connection processes, making it an attractive target for attackers seeking to exploit systems through standard user interactions.
Mitigation strategies for CVE-2017-9831 should focus on immediate patching of affected libmtp versions, with the vulnerability being resolved in version 1.1.13 and later. System administrators should implement device access controls to restrict automatic device connection and processing, particularly for untrusted devices. The implementation of input validation and bounds checking mechanisms within the affected library functions can provide additional protection layers. Organizations should also consider deploying network segmentation and device management policies that limit the scope of potential exploitation. Security monitoring should include detection of unusual device connection patterns and memory access violations that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper integer handling in protocol parsing implementations and highlights the need for comprehensive testing of boundary conditions in device management libraries. Additionally, implementing sandboxing or containerization for device management processes can limit the potential impact of successful exploitation attempts. Regular security audits of third-party libraries and their usage in critical systems should be conducted to identify similar vulnerabilities that might exist in other components of the system stack.