CVE-2017-9696 in Android
Summary
by MITRE
In android for MSM, Firefox OS for MSM, QRD Android, with all Android releases from CAF using the Linux kernel, buffer over-read is possible in camera driver function msm_isp_stop_stats_stream. Variable stream_cfg_cmd->num_streams is from userspace, and it is not checked against "MSM_ISP_STATS_MAX".
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Analysis
by VulDB Data Team • 12/07/2019
The vulnerability identified as CVE-2017-9696 represents a critical buffer over-read condition affecting multiple Android-based platforms including MSM variants, Firefox OS for MSM, and QRD Android implementations. This flaw exists within the camera driver component of the Linux kernel used by these systems, specifically within the msm_isp_stop_stats_stream function. The vulnerability stems from insufficient input validation where the variable stream_cfg_cmd->num_streams originates from userspace and lacks proper bounds checking against the predefined MSM_ISP_STATS_MAX constant, creating a potential exploitation vector for malicious actors seeking to compromise device security.
The technical nature of this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions where a program accesses memory beyond the allocated buffer boundaries. The flaw occurs when the camera driver processes statistics streaming configuration commands without validating that the number of streams specified by userspace applications remains within acceptable limits. This allows attackers to manipulate the stream_cfg_cmd->num_streams parameter to exceed the maximum allowed value of MSM_ISP_STATS_MAX, resulting in memory access violations that could potentially lead to system instability or arbitrary code execution. The vulnerability specifically affects devices running Android releases from the Code Aurora Forum (CAF) that utilize the Linux kernel, making it widespread across numerous mobile platforms.
The operational impact of this vulnerability extends beyond simple memory corruption, as it could enable attackers to exploit the buffer over-read condition to achieve privilege escalation or system compromise. When the camera driver function processes invalid stream count values, the over-read behavior could expose sensitive kernel memory regions to userspace applications, potentially revealing system information or creating opportunities for further exploitation. This vulnerability is particularly concerning in mobile environments where camera functionality is frequently accessed and where attackers might leverage the camera subsystem to gain unauthorized access to device resources, aligning with ATT&CK technique T1059.003 for command and scripting interpreter usage in potentially malicious contexts.
Mitigation strategies for CVE-2017-9696 should focus on implementing proper input validation within the camera driver functions, specifically ensuring that all stream count parameters are validated against predefined maximum limits before processing. System administrators and device manufacturers should prioritize applying security patches from their respective vendors, as the vulnerability affects multiple platform variants and requires coordinated updates across different software components. Additionally, runtime monitoring and input sanitization measures should be implemented to detect and prevent malicious input attempts targeting this specific function. The fix should include bounds checking mechanisms that validate stream_cfg_cmd->num_streams against MSM_ISP_STATS_MAX and return appropriate error codes when validation fails, preventing the buffer over-read condition from occurring. Organizations should also consider implementing security hardening measures such as kernel address space layout randomization and stack canaries to further reduce the exploitability of similar buffer overflow conditions in the camera subsystem.