CVE-2017-8250 in Android
Summary
by MITRE
In all Qualcomm products with Android releases from CAF using the Linux kernel, user controlled variables "nr_cmds" and "nr_bos" number are passed across functions without any check. An integer overflow to buffer overflow (with a smaller buffer allocated) may occur when they are too large or negative.
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Analysis
by VulDB Data Team • 01/14/2021
The vulnerability identified as CVE-2017-8250 represents a critical integer overflow flaw present in Qualcomm products utilizing Android releases from the Code Aurora Forum that incorporate the Linux kernel. This vulnerability stems from insufficient input validation mechanisms within kernel-level functions that process user-controlled data. The flaw specifically involves two variables named "nr_cmds" and "nr_bos" which are passed between functions without proper bounds checking or validation. These variables represent command and buffer object counts respectively, and their unchecked manipulation creates a pathway for malicious exploitation.
The technical implementation of this vulnerability occurs when these user-controllable variables exceed the acceptable range for their designated data types, leading to integer overflow conditions. When such overflows occur, the subsequent buffer allocation calculations become invalid, resulting in the allocation of buffers that are significantly smaller than required. This fundamental miscalculation creates a scenario where the system attempts to write data beyond the allocated buffer boundaries, thereby enabling a classic buffer overflow condition. The vulnerability is particularly concerning because it operates at the kernel level where privilege escalation opportunities exist, potentially allowing attackers to execute arbitrary code with elevated privileges.
The operational impact of CVE-2017-8250 extends beyond simple buffer corruption, as it provides a potential attack vector for privilege escalation and system compromise. Attackers can leverage this vulnerability to manipulate the kernel's memory management functions by feeding malicious values into the "nr_cmds" and "nr_bos" parameters, potentially leading to complete system compromise. The vulnerability affects a broad range of Qualcomm-based devices running Android systems, including smartphones, tablets, and other mobile platforms that utilize the Linux kernel framework. This widespread impact is consistent with the nature of kernel-level vulnerabilities that affect the foundational operating system components. The vulnerability aligns with CWE-190, which specifically addresses integer overflow conditions, and can be mapped to ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation' through kernel exploits.
Mitigation strategies for CVE-2017-8250 require immediate attention from device manufacturers and system administrators. The primary remediation involves implementing proper input validation and bounds checking for the affected variables within the kernel code. This includes adding explicit checks to ensure that "nr_cmds" and "nr_bos" values remain within acceptable ranges before any buffer allocation occurs. The fix should enforce strict type checking and implement overflow detection mechanisms that prevent the propagation of invalid values through kernel functions. Additionally, organizations should consider implementing kernel hardening measures such as stack canaries, address space layout randomization, and other exploit mitigation techniques to reduce the overall attack surface. Regular security updates and patches should be deployed immediately to affected systems, as this vulnerability represents a critical threat that can be exploited remotely without user interaction, making it particularly dangerous in mobile environments where devices are frequently connected to untrusted networks and services.