An issue was discovered on Foscam C2 devices with System Firmware 1.11.1.8 and Application Firmware 2.72.1.32, and Opticam i5 devices with System Firmware 1.5.2.11 and Application Firmware 2.21.1.128. /mnt/mtd/app has 0777 permissions, allowing local users to replace an archive file (within that directory) to control what is extracted to RAM at boot time.