CVE-2017-7367 in Android
Summary
by MITRE
In all Android releases from CAF using the Linux kernel, an integer underflow vulnerability exists while processing the boot image.
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Analysis
by VulDB Data Team • 12/27/2020
The vulnerability identified as CVE-2017-7367 represents a critical integer underflow condition that affects all Android releases utilizing the Linux kernel from the Code Aurora Forum. This flaw manifests during the processing of boot images, which are essential components in the Android operating system's initialization sequence. The vulnerability stems from improper validation of integer values when handling boot image headers, creating a scenario where arithmetic operations can produce results that fall below the minimum representable value for the data type. Such conditions typically occur when a signed integer is decremented below its minimum value, causing it to wrap around to a large positive value, which can lead to unpredictable behavior in the system's memory management and control flow mechanisms.
The technical exploitation of this vulnerability occurs when the Android system processes malformed boot images that contain specially crafted header values designed to trigger the integer underflow condition. When the kernel attempts to calculate memory offsets or buffer sizes based on these corrupted header values, the underflow can result in memory corruption, potentially allowing attackers to execute arbitrary code with elevated privileges. This vulnerability specifically impacts the Android boot process where the kernel parses and validates boot image structures, making it particularly dangerous as it can be triggered during the most critical phase of system initialization. The integer underflow creates a condition where the system may attempt to access memory locations outside the intended bounds, leading to potential code execution or system instability.
The operational impact of CVE-2017-7367 extends beyond simple system crashes or instability, as it represents a potential path to full system compromise. Attackers who can influence the boot image processing, such as through malicious firmware updates or compromised boot sources, can leverage this vulnerability to gain unauthorized access to the device. The vulnerability's presence in all Android releases from CAF using the Linux kernel means that a substantial portion of Android devices remain susceptible to exploitation, particularly those that rely on Qualcomm's kernel implementations. This affects not only mobile devices but also embedded systems and IoT devices that utilize Android-based operating systems, making it a widespread concern for security professionals across multiple domains. The vulnerability can be classified under CWE-191 Integer Underflow or Wraparound, which is a well-documented weakness in software development that often leads to memory corruption issues. From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1059.001 Command and Scripting Interpreter for executing malicious code during the boot process, and T1068 Exploitation for Windows OS, though the latter is more relevant to the exploitation methodology. The vulnerability's nature also relates to T1014 Rootkit as it could potentially allow for persistent backdoor access through compromised boot processes. The integer underflow creates a chain of potential security failures that can be exploited to achieve privilege escalation, making it particularly dangerous in environments where device integrity and secure boot mechanisms are critical for maintaining system security.
Mitigation strategies for CVE-2017-7367 focus primarily on patching the affected kernel implementations and implementing robust input validation during boot image processing. Device manufacturers should ensure that all Android releases are updated with kernel patches that properly validate integer values before arithmetic operations are performed. The recommended approach involves implementing bounds checking and overflow detection mechanisms in the boot image parsing code, ensuring that all header values are validated against expected ranges before any calculations are executed. Additionally, secure boot mechanisms should be strengthened to prevent unauthorized boot image modifications, and runtime integrity checks should be implemented to detect and prevent exploitation attempts. System administrators and security teams should also monitor for any signs of exploitation attempts and ensure that all devices are running patched firmware versions. The vulnerability's remediation requires careful attention to kernel code quality and adherence to secure coding practices, particularly in critical system initialization paths where integer arithmetic is performed. Organizations should also consider implementing network-based detection mechanisms to identify potential exploitation attempts and establish incident response procedures specifically tailored to address boot image-related vulnerabilities.