CVE-2018-11986 in Android
Summary
by MITRE
In all android releases(Android for MSM, Firefox OS for MSM, QRD Android) from CAF using the linux kernel, Possible buffer overflow in TX and RX FIFOs of microcontroller in camera subsystem used to exchange commands and messages between Micro FW and CPP driver.
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Analysis
by VulDB Data Team • 04/22/2020
This vulnerability resides within the Android operating system's camera subsystem where the Linux kernel interfaces with microcontroller firmware through dedicated transmit and receive FIFO buffers. The flaw manifests as a potential buffer overflow condition that occurs during command and message exchanges between the Micro FW and CPP driver components. Such buffer overflows represent a critical security concern as they can enable arbitrary code execution or system crashes when the FIFO buffers exceed their allocated memory boundaries during data transmission.
The technical implementation of this vulnerability stems from inadequate bounds checking within the camera subsystem's firmware communication layer. When the microcontroller processes commands from the CPP driver, the TX and RX FIFO buffers may receive more data than their allocated capacity allows, creating conditions where adjacent memory locations become overwritten. This type of vulnerability maps directly to CWE-121 which defines buffer overflow conditions in stack-based buffers, and CWE-122 which addresses heap-based buffer overflows. The underlying mechanism involves insufficient validation of data length parameters before writing to these fixed-size FIFO structures, allowing malicious data injection that can corrupt system memory.
From an operational perspective, this vulnerability presents significant risks to Android devices utilizing Qualcomm chipsets where the camera subsystem is active. Attackers could potentially exploit this condition to execute arbitrary code with elevated privileges, effectively bypassing standard security boundaries between user-space applications and kernel-level components. The impact extends beyond simple system instability to include complete device compromise, data exfiltration, and persistent backdoor establishment. The vulnerability affects multiple Android variants including MSM, Firefox OS for MSM, and QRD Android, indicating widespread exposure across Qualcomm-based mobile platforms and potentially embedded systems relying on similar microcontroller architectures.
Mitigation strategies should focus on implementing robust input validation mechanisms within the camera subsystem firmware, establishing proper bounds checking for all FIFO operations, and applying kernel-level patches that address the specific buffer overflow conditions. Security researchers recommend implementing stack canaries, address space layout randomization, and memory protection mechanisms to prevent exploitation. Additionally, regular firmware updates and security patches should be deployed immediately upon availability, as the vulnerability affects multiple device generations and manufacturers. Organizations should also consider network-based detection measures to monitor for anomalous camera subsystem behavior that might indicate exploitation attempts, aligning with ATT&CK technique T1059.007 for command and scripting interpreter execution and T1068 for exploit for privilege escalation.