CVE-2018-21084 in Samsung
Summary
by MITRE
An issue was discovered on Samsung mobile devices with L(5.1), M(6.0), and N(7.x) software. There is a race condition with a resultant read-after-free issue in get_kek. The Samsung ID is SVE-2017-11174 (February 2018).
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Analysis
by VulDB Data Team • 10/09/2020
This vulnerability exists in Samsung mobile devices running Android versions Lollipop 5.1, Marshmallow 6.0, and Nougat 7.x operating systems. The issue stems from a race condition that manifests as a read-after-free error within the get_kek function, which is a critical component in the device's cryptographic key management system. The race condition occurs when multiple threads or processes attempt to access and modify the same memory location simultaneously without proper synchronization mechanisms, creating a window where memory can be freed and subsequently accessed by other processes. This particular flaw represents a fundamental weakness in the kernel-level memory management and thread synchronization protocols that Samsung implemented in their mobile device firmware.
The technical exploitation of this vulnerability allows an attacker to manipulate the timing of concurrent operations to trigger the race condition, resulting in a situation where freed memory is accessed after it has been deallocated from the heap. The get_kek function, which is responsible for retrieving encryption keys used in the device's secure element operations, becomes a critical attack vector when this memory management flaw is exploited. This read-after-free condition can potentially be leveraged to execute arbitrary code with elevated privileges, as the attacker can manipulate the contents of the freed memory location to inject malicious instructions or manipulate kernel data structures. The vulnerability specifically targets the cryptographic key extraction process, making it particularly dangerous for devices that rely heavily on secure key management for encryption, authentication, and secure communications.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it compromises the fundamental security architecture of Samsung mobile devices. Attackers who successfully exploit this race condition can potentially gain root access to the device, enabling them to bypass all security controls, extract sensitive data, modify system files, and install malicious applications without user consent. The vulnerability affects a significant range of Samsung devices that were shipped with these Android versions, creating a widespread security concern across multiple device models and generations. This type of vulnerability is particularly concerning in mobile environments where devices handle sensitive personal information, financial data, and corporate communications, making the exploitation potential extremely high for threat actors targeting mobile device security.
Mitigation strategies for this vulnerability primarily involve applying the official security patches released by Samsung and Google as part of their regular security updates. The fix typically involves implementing proper synchronization mechanisms to prevent the race condition from occurring, such as mutex locks or atomic operations that ensure exclusive access to shared resources during key management operations. Organizations should prioritize immediate deployment of the security patches and consider implementing additional monitoring controls to detect potential exploitation attempts. From a defensive perspective, this vulnerability aligns with CWE-362, which describes race conditions in software systems, and represents a classic example of how improper concurrency control can lead to critical security flaws. The ATT&CK framework categorizes this type of vulnerability under privilege escalation techniques, specifically targeting kernel-level exploits that leverage memory corruption vulnerabilities to gain elevated system privileges. Device manufacturers and security teams should also consider implementing runtime protections and memory integrity checks to detect and prevent exploitation attempts, while maintaining awareness of similar vulnerabilities that may exist in other cryptographic implementations within mobile device ecosystems.