CVE-2017-14201 in Zephyr Shell
Summary
by MITRE
Use After Free vulnerability in the Zephyr shell allows a serial or telnet connected user to cause denial of service, and possibly remote code execution. This issue affects: Zephyr shell versions prior to 1.14.0 on all.
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Analysis
by VulDB Data Team • 12/07/2023
The vulnerability identified as CVE-2017-14201 represents a critical use-after-free flaw within the Zephyr shell component that operates within the Zephyr operating system framework. This security weakness specifically targets versions prior to 1.14.0 and manifests through serial or telnet connections, creating a pathway for malicious actors to exploit the system. The Zephyr shell serves as a command-line interface for interacting with embedded systems running the Zephyr RTOS, making this vulnerability particularly concerning for IoT and embedded device deployments where remote access capabilities are prevalent.
The technical nature of this use-after-free vulnerability stems from improper memory management within the shell's handling of user input and command processing. When a user establishes a serial or telnet connection and executes specific commands, the shell fails to properly validate or manage memory references, leading to situations where freed memory blocks are accessed after they have been deallocated. This memory management error creates a condition where attackers can manipulate the system's memory state to execute arbitrary code or cause system crashes. The vulnerability operates at the application layer within the Zephyr shell implementation and can be triggered through legitimate user interaction with the system's command interface.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, presenting potential for remote code execution that could compromise entire embedded systems. An attacker with access to a serial or telnet connection can leverage this flaw to gain unauthorized control over the device, potentially leading to data exfiltration, system compromise, or disruption of critical services. The severity classification of this vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software implementations. This weakness enables adversaries to exploit the memory management flaw through the established communication channels, making it particularly dangerous in environments where remote access is enabled by default or where untrusted users have connectivity privileges.
Organizations utilizing Zephyr-based systems must implement immediate mitigation strategies to address this vulnerability. The primary recommendation involves upgrading to Zephyr shell version 1.14.0 or later, which contains the necessary patches to prevent the use-after-free condition. Additionally, administrators should consider implementing network segmentation to limit access to serial and telnet interfaces, disabling unnecessary remote access capabilities, and monitoring for suspicious connection patterns. The ATT&CK framework categorizes this vulnerability under the T1059.007 technique for command and scripting interpreter, specifically targeting remote access through network services. Security teams should also consider implementing intrusion detection systems to monitor for exploitation attempts and establish incident response procedures to address potential compromise scenarios. The vulnerability demonstrates how seemingly minor memory management errors can create significant security risks in embedded systems where resource constraints and remote access capabilities intersect.