CVE-2017-11093 in Android
Summary
by MITRE
In android for MSM, Firefox OS for MSM, QRD Android, with all Android releases from CAF using the Linux kernel, buffer Over-read in Display due to the lack of an upper-bound validation when reading "num_of_cea_blocks" from the untrusted source (EDID), kernel memory can be exposed.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 12/07/2019
This vulnerability exists in android for msm firefox os for msm qrd android and all android releases from caf using the linux kernel where a buffer over-read occurs in the display subsystem. The flaw stems from insufficient input validation when processing the "num_of_cea_blocks" field from the Extended Display Identification Data (EDID) structure which is an untrusted source typically provided by display hardware. The absence of upper-bound validation allows malicious actors to manipulate this field and cause the kernel to read beyond allocated memory boundaries. This particular vulnerability falls under the common weakness enumeration category of CWE-125 out-of-bounds read which represents a fundamental flaw in memory safety where programs access memory locations beyond the intended buffer limits. The operational impact of this vulnerability is significant as it can lead to information disclosure where kernel memory contents become accessible to unauthorized users or processes. Attackers can exploit this by crafting malicious EDID data with manipulated num_of_cea_blocks values that cause the kernel driver to traverse into adjacent memory regions. This exposure can potentially reveal sensitive kernel data including cryptographic keys, credentials, or other confidential information stored in memory. The attack surface is particularly concerning in mobile environments where the linux kernel handles display communication protocols and where the EDID data originates from external display devices such as monitors or projectors. The vulnerability represents a critical security risk within the ATT&CK framework under the technique of privilege escalation and information gathering as it allows for kernel memory exposure without requiring elevated privileges. The exploitability of this vulnerability is enhanced by the fact that EDID data is automatically processed by the kernel without sufficient validation, making it an ideal target for supply chain attacks or physical display device manipulation. Mitigation strategies should include implementing proper bounds checking for all EDID fields, particularly num_of_cea_blocks, and establishing robust input validation mechanisms within the kernel display drivers. Additionally, kernel memory protection mechanisms such as stack canaries and memory randomization should be employed to further reduce the attack surface. System administrators should also consider implementing device firmware updates and kernel patches that address the specific buffer over-read condition in the display subsystem. The vulnerability highlights the importance of secure coding practices in kernel space where untrusted input from hardware components must be rigorously validated before processing to prevent information disclosure and potential privilege escalation attacks.