CVE-2017-15856 in Android
Summary
by MITRE
Due to a race condition while processing the power stats debug file to read status, a double free condition can occur in Android releases from CAF using the linux kernel (Android for MSM, Firefox OS for MSM, QRD Android) before security patch level 2018-06-05.
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Analysis
by VulDB Data Team • 04/03/2023
This vulnerability represents a critical race condition flaw in Android-based systems that utilize Qualcomm Snapdragon chipsets and the Linux kernel. The issue manifests during the processing of power statistics debug files, where concurrent access patterns create an environment conducive to memory corruption. The double free condition occurs when the system attempts to release the same memory block twice, leading to potential arbitrary code execution or system instability. This vulnerability affects multiple Android variants including Android for MSM, Firefox OS for MSM, and QRD Android platforms, making it particularly widespread across Qualcomm-based devices.
The technical root cause stems from improper synchronization mechanisms within the kernel's debug file processing subsystem. When multiple threads or processes attempt to access the power statistics debug interface simultaneously, the race condition allows for a scenario where a memory allocation is freed by one process while another process simultaneously attempts to free the same memory region. This creates a heap corruption state that can be exploited to manipulate kernel memory structures. The vulnerability is classified under CWE-367, which specifically addresses Time-of-Check to Time-of-Use (TOCTOU) race conditions, and aligns with ATT&CK technique T1068 which covers local privilege escalation through kernel exploits.
The operational impact of this vulnerability extends beyond simple system crashes, as it provides potential attackers with pathways for privilege escalation and persistent system compromise. Attackers can leverage the double free condition to execute arbitrary code with kernel-level privileges, effectively bypassing traditional security boundaries. This makes the vulnerability particularly dangerous in mobile environments where kernel-level access enables complete device compromise, including access to encrypted data, persistent backdoors, and full system control. The vulnerability affects devices shipped with security patches prior to June 5th, 2018, leaving millions of devices potentially exposed to exploitation.
Mitigation strategies should focus on applying the security patches released by Qualcomm and device manufacturers, which address the race condition through proper synchronization mechanisms and memory management protocols. System administrators should implement immediate patch deployment across all affected devices, particularly those in enterprise environments where device compromise could lead to significant data breaches. Additionally, monitoring for suspicious kernel memory access patterns and implementing kernel hardening measures such as stack canaries and memory randomization can provide additional defense-in-depth layers. Organizations should also consider implementing device enrollment and patch management systems to ensure timely remediation of similar vulnerabilities, as this type of race condition vulnerability often indicates broader architectural weaknesses in concurrent system design that may be exploited in other contexts.