CVE-2022-20073 in MT2601
Summary
by MITRE • 04/12/2022
In preloader (usb), there is a possible out of bounds write due to a integer underflow. This could lead to local escalation of privilege, for an attacker who has physical access to the device, with no additional execution privileges needed. User interaction is needed for exploitation. Patch ID: ALPS06160841; Issue ID: ALPS06160841.
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Analysis
by VulDB Data Team • 04/17/2022
The vulnerability identified as CVE-2022-20073 resides within the preloader component of USB functionality in Android devices, representing a critical security flaw that exploits an integer underflow condition leading to potential out-of-bounds write operations. This vulnerability specifically affects the preloader module responsible for handling USB connections and device initialization processes, making it a prime target for privilege escalation attacks. The integer underflow occurs when the preloader fails to properly validate input parameters during USB communication handling, creating a scenario where an attacker can manipulate memory boundaries through crafted USB data sequences.
The technical exploitation of this vulnerability requires an attacker to possess physical access to the target device, which aligns with the ATT&CK technique T1211 - Exploitation for Privilege Escalation and T1059 - Command and Scripting Interpreter. The integer underflow condition manifests when the preloader processes USB data structures containing maliciously crafted values that cause arithmetic operations to produce negative results, subsequently leading to memory corruption. This flaw is classified under CWE-129 - Improper Validation of Array Index, which specifically addresses the lack of proper validation of array indices and other loop or access bounds, directly correlating to the out-of-bounds write scenario. The vulnerability's impact is particularly severe because it operates at a low system level within the preloader phase, which typically executes before the operating system fully initializes.
From an operational perspective, this vulnerability creates a significant risk for devices that support USB debugging or have USB interfaces enabled, as it can be exploited to gain local privilege escalation without requiring additional execution privileges. The requirement for physical access limits the attack surface but does not eliminate the threat, particularly in environments where devices may be left unattended or where attackers can gain access to devices through social engineering or other means. The need for user interaction during exploitation suggests that the attack vector involves some form of USB connection initiation or device interaction that triggers the vulnerable code path. This characteristic makes the vulnerability particularly concerning for mobile devices where users frequently connect to various USB peripherals, including chargers, computers, or specialized hardware that might be compromised.
The patch ID ALPS06160841 addresses this vulnerability through proper input validation and boundary checking mechanisms within the preloader USB handling code. The mitigation strategy involves implementing robust integer overflow/underflow checks before any array access operations, ensuring that all USB data parameters are validated against expected ranges. Security practitioners should prioritize patch deployment for affected devices and consider implementing additional security controls such as USB interface restrictions, device enrollment policies, and monitoring for unauthorized USB connections. Organizations should also conduct security assessments to identify devices running vulnerable firmware versions and implement device management solutions that can enforce security policies and prevent exploitation attempts. The vulnerability demonstrates the importance of secure coding practices in low-level system components and highlights the need for comprehensive security testing of pre-boot and boot-time processes where traditional security controls may not be fully effective.