CVE-2021-0455 in Android
Summary
by MITRE • 03/11/2021
In the Citadel chip firmware, there is a possible out of bounds write due to a missing bounds check. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-175116439
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Analysis
by VulDB Data Team • 03/31/2021
The vulnerability identified as CVE-2021-0455 resides within the Citadel chip firmware component of Android systems, representing a critical security flaw that could enable local privilege escalation. This issue manifests as an out-of-bounds write condition that occurs due to the absence of proper bounds checking mechanisms within the firmware code. The vulnerability specifically affects Android kernel implementations and has been catalogued with the Android ID A-175116439, indicating its classification within the Android security framework. The absence of bounds validation creates a scenario where malicious code can write data beyond the allocated memory boundaries, potentially corrupting adjacent memory regions or executing arbitrary code with elevated privileges.
The technical nature of this vulnerability places it squarely within the scope of CWE-129, which addresses insufficient bounds checking in software systems. This weakness allows attackers to manipulate memory structures and potentially overwrite critical system data or function pointers, leading to unauthorized privilege escalation. The exploitability of this vulnerability requires only local system access and System execution privileges, making it particularly dangerous as it can be leveraged by malicious applications or processes already running with elevated permissions. Unlike many other vulnerabilities that require user interaction or network-based exploitation, this flaw can be triggered through local system calls or firmware interactions, significantly reducing the attack surface and increasing the potential impact.
From an operational perspective, this vulnerability presents a severe risk to Android device security as it enables local privilege escalation without requiring user interaction or network connectivity. The implications extend beyond simple privilege elevation, as successful exploitation could allow attackers to bypass security mechanisms, modify system files, or establish persistent access to the device. The requirement for System execution privileges suggests that this vulnerability may be exploitable by malicious applications that have already gained elevated access to the system, potentially through other attack vectors or through legitimate system processes. The memory corruption resulting from the out-of-bounds write could manifest in various ways including system crashes, data corruption, or complete system compromise depending on the specific memory locations overwritten.
Mitigation strategies for CVE-2021-0455 should focus on firmware updates and patches provided by device manufacturers, as the vulnerability exists at the hardware firmware level. System administrators and device manufacturers should prioritize the deployment of security patches that implement proper bounds checking mechanisms within the Citadel chip firmware. The remediation process must ensure comprehensive testing of firmware updates to prevent regression issues while maintaining device functionality. Additionally, implementing runtime protection mechanisms such as stack canaries, address space layout randomization, and memory protection features can provide additional layers of defense. Organizations should also consider monitoring for suspicious system behavior that might indicate exploitation attempts, particularly around memory allocation and system call patterns. The vulnerability's classification under the ATT&CK framework would likely fall under privilege escalation techniques, specifically targeting the use of firmware-level vulnerabilities to gain elevated system access. Regular security assessments and vulnerability scanning should be implemented to identify similar bounds checking issues within other system components, as this type of vulnerability often indicates broader code quality or security implementation gaps that may affect other firmware or software modules.