CVE-2017-9723 in Android
Summary
by MITRE
The touchscreen driver synaptics_dsx in Android for MSM, Firefox OS for MSM, and QRD Android before 2017-06-05, the size of a stack-allocated buffer can be set to a value which exceeds the size of the stack.
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Analysis
by VulDB Data Team • 02/24/2023
The vulnerability identified as CVE-2017-9723 affects the synaptics_dsx touchscreen driver component across multiple Android-based platforms including MSM variants, Firefox OS for MSM, and QRD Android systems. This issue represents a classic buffer overflow condition that occurs within the kernel-level touchscreen driver responsible for handling touch input events on mobile devices. The vulnerability specifically impacts systems running versions prior to the 2017-06-05 security update, leaving millions of devices potentially exposed to exploitation.
The technical flaw manifests in the improper validation of buffer size parameters within the synaptics_dsx driver implementation. When processing touchscreen input data, the driver allocates a stack-based buffer whose size is determined by user-supplied parameters from the input stream. This design flaw allows an attacker to manipulate the buffer size parameter to exceed the allocated stack space, creating a condition where subsequent memory operations can overwrite adjacent stack variables and potentially execute arbitrary code. The vulnerability is categorized under CWE-121 as a stack-based buffer overflow, which represents a well-known class of memory corruption vulnerabilities that have been exploited extensively in mobile platforms.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable full system compromise. An attacker with the ability to send specially crafted input data to the touchscreen driver could leverage this buffer overflow to execute arbitrary code with kernel-level privileges. This would allow for complete system compromise including persistent backdoor installation, data exfiltration, and privilege escalation attacks. The attack surface is particularly concerning given that touchscreen drivers are continuously active and receive input from untrusted sources, making exploitation relatively straightforward from a remote or local attacker perspective.
From an adversary perspective, this vulnerability aligns with ATT&CK technique T1068 which involves exploiting vulnerabilities in operating systems or applications to gain elevated privileges. The attack vector typically involves crafting malicious touch input sequences that trigger the buffer overflow condition during driver processing. Mitigation strategies should focus on immediate patch deployment for all affected Android variants and Firefox OS implementations, along with runtime protections such as stack canaries and address space layout randomization. Additionally, implementing proper input validation within the driver code to enforce strict bounds checking on buffer size parameters would prevent the exploitation of this vulnerability while maintaining system functionality and performance.