CVE-2024-23935 in Halo9
Summary
by MITRE • 09/28/2024
Alpine Halo9 DecodeUTF7 Stack-based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of Alpine Halo9 devices. An attacker must first obtain the ability to pair a malicious Bluetooth device with the target system in order to exploit this vulnerability.
The specific flaw exists within the DecodeUTF7 function. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of root.
Was ZDI-CAN-23249
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Analysis
by VulDB Data Team • 03/22/2025
The CVE-2024-23935 vulnerability represents a critical stack-based buffer overflow affecting Alpine Halo9 devices that enables remote code execution with root privileges. This vulnerability resides within the DecodeUTF7 function, a component responsible for processing UTF-7 encoded data streams. The flaw stems from inadequate input validation where user-supplied data length is not properly verified before being copied into a fixed-size stack buffer. This type of vulnerability maps directly to CWE-121 Stack-based Buffer Overflow, which is classified as a high-severity weakness in the Common Weakness Enumeration catalog. The vulnerability's exploitation requires an attacker to first establish a Bluetooth pairing relationship with the target device, positioning this issue within the ATT&CK framework under the T1133 command and control category where initial access is gained through device pairing mechanisms.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious UTF-7 encoded data that exceeds the allocated stack buffer size during the DecodeUTF7 processing. This buffer overflow allows attackers to overwrite adjacent stack memory, potentially including return addresses and control flow information. The vulnerability's remote execution capability is facilitated through the Bluetooth pairing mechanism, which serves as the initial attack vector. Once a malicious device is paired with the target system, the attacker can send specially crafted UTF-7 encoded data that triggers the buffer overflow condition. The exploitation chain typically involves sending malformed UTF-7 data through the Bluetooth connection, which when processed by the DecodeUTF7 function causes the stack buffer to overflow and potentially execute arbitrary code with the highest privilege level available on the system.
The operational impact of this vulnerability is severe as it provides attackers with complete system compromise and root-level access to affected Alpine Halo9 devices. The vulnerability affects devices that process UTF-7 encoded data through the DecodeUTF7 function, which likely occurs in various communication protocols and data processing scenarios. Given that the attack requires only Bluetooth pairing access, the attack surface is relatively broad as many devices may be vulnerable to unauthorized pairing attempts. The root privilege escalation capability means that attackers can gain complete control over the device's operating system, potentially leading to data exfiltration, persistent backdoor installation, or use of the compromised device as a pivot point for further attacks within network environments. This vulnerability particularly impacts IoT and embedded systems where device pairing mechanisms may not implement robust security controls.
Mitigation strategies for CVE-2024-23935 should focus on both immediate patching and operational security improvements. The primary remediation involves applying firmware updates from Alpine that address the buffer overflow in the DecodeUTF7 function through proper input validation and length checking mechanisms. Organizations should implement Bluetooth pairing security controls including strong authentication requirements, pairing restrictions, and regular monitoring of pairing relationships. Network segmentation and access controls should be enforced to limit Bluetooth communication to authorized devices only. Additionally, implementing network-based intrusion detection systems can help identify suspicious Bluetooth pairing attempts and malformed UTF-7 data streams. Security teams should also consider disabling unnecessary Bluetooth functionality when not required for device operation. The vulnerability's classification as a remote code execution issue with root privileges necessitates immediate attention and comprehensive security posture review across all affected Alpine Halo9 deployments.