CVE-2019-20548 in Samsung
Summary
by MITRE
An issue was discovered on Samsung mobile devices with P(9.0) devices (Qualcomm chipsets) software. There is a buffer overflow in the bootloader. The Samsung ID is SVE-2019-15399 (November 2019).
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Analysis
by VulDB Data Team • 10/04/2020
The vulnerability identified as CVE-2019-20548 represents a critical buffer overflow condition within the bootloader component of Samsung mobile devices running Android 9.0 (Pie) with Qualcomm chipsets. This issue affects the device's initial boot process where the bootloader is responsible for loading the operating system and establishing the secure execution environment. The buffer overflow occurs during the bootloader's processing of specific input data, creating a potential entry point for malicious actors to compromise the device's integrity before the operating system fully loads.
The technical flaw manifests as an improper bounds checking mechanism within the bootloader's memory management functions. When processing certain input parameters or firmware updates, the bootloader fails to validate the size of incoming data against the allocated buffer space, allowing attackers to write beyond the intended memory boundaries. This vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, and specifically relates to the improper handling of memory allocation during device boot processes. The flaw is particularly dangerous because it operates at the lowest level of the device's software stack, making it difficult to detect and exploit through conventional means.
The operational impact of this vulnerability extends beyond simple data corruption, as it provides potential attackers with the capability to execute arbitrary code during the boot process, effectively bypassing the device's security mechanisms. This allows for complete device compromise before the operating system's security features can be activated, creating a persistent backdoor that could be exploited to install malware, extract sensitive data, or modify the device's firmware. Attackers could potentially leverage this vulnerability to gain root access to devices, undermining the security model that relies on the integrity of the boot process. The vulnerability's classification aligns with ATT&CK technique T1068, which describes the use of local privilege escalation through boot or logon initialization scripts.
Mitigation strategies for CVE-2019-20548 require immediate firmware updates from Samsung, as the vulnerability exists within the bootloader itself and cannot be patched through standard operating system updates. Organizations should implement device enrollment programs to ensure timely patch deployment and consider network segmentation to limit the potential impact of compromised devices. The vulnerability also highlights the importance of secure boot implementations and proper input validation in firmware components, as recommended by industry standards such as NIST SP 800-155 for mobile device security. Device manufacturers should implement robust memory safety mechanisms and regular security audits of bootloader components to prevent similar issues in future releases.