CVE-2017-13247 in Android
Summary
by MITRE
In the Pixel 2 bootloader, there is a missing permission check which bypasses carrier bootloader lock. This could lead to local elevation of privileges with user execution privileges needed. User interaction is not needed for exploitation. Product: Android. Versions: Android kernel. Android ID: A-71486645.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 01/04/2020
The vulnerability identified as CVE-2017-13247 represents a critical security flaw within the Pixel 2 bootloader implementation that fundamentally undermines the device's security architecture. This issue resides in the Android kernel and specifically targets the bootloader's permission validation mechanisms, creating a pathway for unauthorized system modifications that bypass essential carrier security controls. The vulnerability's classification as a missing permission check aligns with CWE-284, which addresses improper access control vulnerabilities that allow unauthorized users to perform privileged operations.
The technical nature of this flaw stems from inadequate verification processes within the bootloader's initialization sequence, where carrier-specific locking mechanisms fail to properly validate authorization levels before permitting system modifications. This weakness allows an attacker with local execution privileges to circumvent the bootloader's intended security boundaries, effectively removing the carrier lock that normally prevents unauthorized firmware modifications. The exploitation requires only user-level execution privileges without any need for additional user interaction, making it particularly dangerous as it can be triggered automatically during normal device operation.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with the ability to modify critical system components that are typically protected by hardware and software security mechanisms. This includes the potential to install malicious firmware versions, modify boot parameters, or disable security features that protect the device from other attack vectors. The vulnerability affects the Android kernel specifically, which means that any device running Android with the affected bootloader implementation is susceptible to this attack, particularly those manufactured with Pixel 2 hardware specifications.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1068, which covers "Local Privilege Escalation" and T1542, covering "Pre-OS Boot" attack methods that manipulate system boot processes. The lack of user interaction requirement makes this particularly concerning as it can be exploited silently in the background, potentially allowing attackers to establish persistent backdoors or deploy malware that can survive device reboots. Security researchers have noted that such bootloader-level vulnerabilities are particularly dangerous because they can be leveraged to create rootkits or other persistent threats that operate below the normal operating system security layers.
Mitigation strategies for this vulnerability require immediate implementation of firmware updates from Google and device manufacturers, as well as consideration of carrier-specific security patches that address the bootloader permission validation gaps. System administrators and security professionals should also implement monitoring solutions that can detect unauthorized bootloader modifications or suspicious boot parameter changes. The vulnerability highlights the importance of proper access control implementation in low-level system components and demonstrates why security-by-design principles must be applied rigorously to bootloader and firmware code. Organizations should also consider implementing device integrity checking mechanisms and secure boot validation processes to prevent exploitation of similar permission bypass vulnerabilities in other system components.