CVE-2017-15854 in Android
Summary
by MITRE
The value of fix_param->num_chans is received from firmware and if it is too large, an integer overflow can occur in wma_radio_chan_stats_event_handler() for the derived length len leading to a subsequent buffer overflow in all Android releases from CAF (Android for MSM, Firefox OS for MSM, QRD Android) using the Linux Kernel.
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Analysis
by VulDB Data Team • 02/18/2020
The vulnerability described in CVE-2017-15854 represents a critical integer overflow condition within the wireless media access layer driver of Android-based devices. This flaw exists in the wma_radio_chan_stats_event_handler() function where the fix_param->num_chans value is processed directly from firmware input without proper validation. The vulnerability affects multiple Android variants including CAF Android for MSM, Firefox OS for MSM, and QRD Android, indicating a widespread impact across Qualcomm-based mobile platforms. The integer overflow occurs when the received parameter exceeds acceptable bounds, causing the derived length calculation to wrap around and produce an unexpectedly large value that subsequently leads to buffer overflow conditions.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within the wireless driver subsystem. When firmware provides the num_chans parameter, the system fails to perform proper bounds checking before using this value in subsequent calculations. This particular flaw resides in the Linux kernel components that handle wireless communication statistics, specifically within the WMA (Wireless Media Access) layer responsible for managing radio channel statistics events. The overflow condition manifests when the integer value representing channel count exceeds the maximum representable value for the data type used in the length calculation, causing the resulting length variable to become negative or excessively large. This mathematical overflow directly translates into a buffer overflow scenario where memory allocation based on the corrupted length value exceeds the intended buffer boundaries.
The operational impact of this vulnerability extends across multiple Android releases and device types, making it particularly dangerous for widespread exploitation. Mobile devices running affected Android versions are susceptible to arbitrary code execution when the overflow occurs during wireless communication processing. Attackers can potentially leverage this vulnerability to escalate privileges, gain unauthorized access to device resources, or even compromise the entire system through memory corruption attacks. The vulnerability's presence in CAF Android for MSM, Firefox OS for MSM, and QRD Android indicates that it affects both mainstream smartphone platforms and specialized device variants, creating a broad attack surface. Additionally, the Linux kernel integration means that the exploitation could potentially affect not just mobile devices but also embedded systems relying on similar wireless communication stacks.
Mitigation strategies for this vulnerability should focus on implementing robust input validation and bounds checking within the wireless driver subsystem. The recommended approach involves adding explicit validation checks for the num_chans parameter before any calculations are performed, ensuring that the value remains within acceptable ranges defined by the system's hardware capabilities and memory constraints. Security patches should include proper integer overflow detection mechanisms that prevent the calculation from producing invalid results when input parameters exceed expected bounds. Organizations should prioritize updating affected Android devices to patched versions that include enhanced validation routines in the wma_radio_chan_stats_event_handler() function. The implementation should follow established security practices such as those outlined in the CWE-190 category for integer overflow vulnerabilities, and consider defensive programming techniques that align with ATT&CK framework mitigation strategies for privilege escalation and code execution attacks. System administrators should also implement network monitoring to detect anomalous wireless communication patterns that might indicate exploitation attempts.