CVE-2017-15836 in Android
Summary
by MITRE
In Qualcomm Android for MSM, Firefox OS for MSM, and QRD Android with all Android releases from CAF using the Linux kernel before security patch level 2018-04-05, if the firmware sends a service ready event to the host with a large number in the num_hw_modes or num_phy, then it could result in an integer overflow which may potentially lead to a buffer overflow.
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Analysis
by VulDB Data Team • 01/21/2020
The vulnerability identified as CVE-2017-15836 represents a critical integer overflow flaw affecting Qualcomm Android devices, Firefox OS for MSM, and QRD Android systems utilizing Linux kernel versions prior to the 2018-04-05 security patch level. This issue stems from insufficient input validation within the firmware communication protocols that handle service ready events. The flaw manifests when the firmware transmits service ready events containing excessively large values in either the num_hw_modes or num_phy fields, creating conditions where integer arithmetic operations exceed their maximum representable values. This vulnerability falls under the CWE-190 category of Integer Overflow or Wraparound, which is a well-documented weakness in software systems where arithmetic operations produce results that exceed the maximum value that can be stored in the target data type.
The technical implementation of this vulnerability occurs at the interface between firmware components and the host operating system, specifically within the communication protocols used for device initialization and hardware mode negotiation. When the firmware sends a service ready event with inflated hardware mode counts or PHY (Physical Layer) specifications, the host system's kernel processing code fails to properly validate these values before performing subsequent memory allocation or buffer operations. This processing error creates a scenario where the system calculates buffer sizes based on the overflowed integer values, potentially resulting in memory regions being allocated with insufficient space or with negative values that cause memory corruption. The vulnerability operates at the kernel level within the Linux kernel's wireless subsystem, making it particularly dangerous as it can be exploited to execute arbitrary code with kernel privileges.
The operational impact of CVE-2017-15836 extends beyond simple denial-of-service conditions to potentially enable full system compromise and persistent backdoor access. Attackers who can trigger this vulnerability through malicious firmware updates or compromised communication channels can exploit the resulting buffer overflow to execute code on affected devices. This capability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter, as well as T1068 for Exploitation for Privilege Escalation, since successful exploitation allows attackers to gain elevated privileges within the device's operating environment. The vulnerability affects a broad range of Qualcomm-based devices including smartphones, tablets, and embedded systems that rely on the affected kernel versions, making it particularly concerning from a supply chain security perspective.
Mitigation strategies for this vulnerability require immediate implementation of security patches provided by Qualcomm and device manufacturers, with particular attention to ensuring all devices receive the 2018-04-05 security update or later. System administrators should implement firmware integrity checks and monitor for unauthorized firmware modifications that could exploit this vulnerability. Network-level defenses should include monitoring for anomalous service ready event patterns that might indicate exploitation attempts, while endpoint protection solutions should be configured to detect and prevent buffer overflow exploitation techniques. The vulnerability's classification as a kernel-level issue necessitates comprehensive system hardening measures including disabling unnecessary wireless services, implementing proper access controls, and maintaining up-to-date security configurations. Organizations should also consider implementing device authentication mechanisms to prevent unauthorized firmware updates that could introduce malicious payloads designed to exploit this integer overflow condition.