CVE-2019-20581 in Samsung
Summary
by MITRE
An issue was discovered on Samsung mobile devices with N(7.x), O(8.x), and P(9.0) (Exynos chipsets) software. A stack overflow in the HDCP Trustlet causes arbitrary code execution. The Samsung ID is SVE-2019-14665 (August 2019).
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Analysis
by VulDB Data Team • 10/04/2020
The vulnerability identified as CVE-2019-20581 represents a critical stack overflow flaw within the HDCP Trustlet component of Samsung mobile devices running Android versions 7.x, 8.x, and 9.0 specifically on Exynos chipsets. This issue resides in the hardware-based copy protection system that manages high-bandwidth digital content protection protocols. The HDCP Trustlet operates as a security-critical component responsible for authenticating and managing digital content encryption keys, making it a prime target for attackers seeking to escalate privileges and execute malicious code. The vulnerability was formally acknowledged by Samsung under the identifier SVE-2019-14665 and reported in August 2019, highlighting the sophisticated nature of the attack surface.
The technical exploitation of this stack overflow occurs within the Trustlet environment which operates in a secure execution context separate from the main operating system. This flaw allows an attacker to manipulate input parameters passed to the HDCP Trustlet, causing a buffer overflow that overwrites adjacent memory locations in the stack. The vulnerability stems from insufficient input validation and bounds checking within the Trustlet's processing routines, creating a condition where malicious data can overwrite return addresses and function pointers. This type of vulnerability maps directly to CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of how secure enclaves can become attack vectors when proper input sanitization fails. The attack typically requires the exploitation of a legitimate interface to the Trustlet, often through HDMI or display subsystem calls that trigger the vulnerable code path.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with the ability to execute arbitrary code within the secure Trustlet environment. This capability enables potential attacks such as full device compromise, persistence mechanisms, and access to encrypted content keys that protect premium digital media. The vulnerability affects millions of Samsung devices through the Exynos chipset family, creating a widespread attack surface that could be leveraged for sophisticated campaigns targeting high-value users or specific geographic regions. The Trustlet's role in content protection means that successful exploitation could lead to unauthorized decryption of protected media, undermining the entire digital rights management ecosystem that Samsung and content providers rely upon. This vulnerability directly aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as attackers could potentially use the arbitrary code execution to establish persistent access or deploy additional malware within the secure execution environment.
Mitigation strategies for CVE-2019-20581 require both immediate and long-term approaches to address the underlying Trustlet implementation flaws. Samsung's official patch addresses the issue through firmware updates that include proper bounds checking and input validation within the HDCP Trustlet routines, preventing the stack overflow condition from occurring. Organizations should implement comprehensive device management policies that ensure timely deployment of security patches across all affected Samsung devices, particularly those in enterprise environments where the risk of targeted attacks is higher. Network monitoring solutions should be configured to detect unusual patterns in HDMI or display interface communications that might indicate exploitation attempts. The vulnerability demonstrates the importance of secure coding practices in trusted execution environments and highlights the need for regular security assessments of components operating within secure enclaves. Additionally, implementing device integrity checks and runtime monitoring can help detect anomalous behavior that might indicate exploitation attempts. Given the nature of the flaw, it is essential that security teams maintain awareness of the specific Exynos chipset models affected and ensure proper patch management protocols are in place to prevent exploitation across the enterprise fleet.