CVE-2019-20561 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. The bootloader has an integer signedness error. The Samsung ID is SVE-2019-15230 (October 2019).
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Analysis
by VulDB Data Team • 10/04/2020
The vulnerability identified as CVE-2019-20561 represents a critical security flaw within the bootloader of Samsung mobile devices running Android versions 7.x, 8.x, and 9.0, specifically affecting devices with Exynos chipsets. This issue stems from an integer signedness error that fundamentally compromises the device's boot process integrity and overall security posture. The vulnerability was officially acknowledged by Samsung under their internal tracking system as SVE-2019-15230, highlighting the severity of the flaw within their security assessment framework.
The technical root cause of this vulnerability lies in the bootloader's handling of integer values where signedness assumptions are improperly managed during critical boot operations. This integer signedness error creates a condition where the bootloader fails to properly validate or process signed integer values during the boot sequence, potentially allowing malicious actors to manipulate the boot process. The flaw exists at the firmware level, making it particularly dangerous as it operates below the operating system layer and can affect the entire device boot chain.
The operational impact of this vulnerability extends beyond simple device compromise, as it creates potential pathways for attackers to bypass secure boot mechanisms and execute unauthorized code during the device initialization process. This allows for persistent rootkit installations, firmware modifications, and complete device control without user knowledge. The vulnerability affects a substantial portion of Samsung's mobile device portfolio, particularly those utilizing Exynos chipsets, making it a widespread concern for both individual users and enterprise deployments.
From a cybersecurity perspective, this vulnerability aligns with CWE-191, which specifically addresses integer underflow and overflow conditions, and represents a clear example of how low-level firmware flaws can create cascading security risks. The ATT&CK framework categorizes this type of vulnerability under the T1068 technique for "Exploitation for Privilege Escalation" as it enables attackers to gain elevated privileges through manipulation of boot processes. The integer signedness error creates an exploitable condition that can be leveraged to establish persistent backdoors, making it particularly attractive to advanced persistent threat actors and malware developers.
Mitigation strategies for this vulnerability primarily involve firmware updates from Samsung, which address the integer signedness error in the bootloader implementation. Users should immediately install available security patches and firmware updates through official Samsung channels. Organizations deploying affected devices should implement comprehensive device management policies that enforce timely security updates and monitor for any signs of exploitation attempts. Additionally, network administrators should consider implementing device authentication and monitoring solutions to detect potential exploitation attempts, as the vulnerability's low-level nature makes traditional endpoint protection measures less effective in preventing exploitation.