CVE-2022-36557 in SkyBridge MB-A100
Summary
by MITRE • 08/30/2022
Seiko SkyBridge MB-A100/A110 v4.2.0 and below was discovered to contain an arbitrary file upload vulnerability via the restore backup function. This vulnerability allows attackers to execute arbitrary code via a crafted html file.
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Analysis
by VulDB Data Team • 10/10/2022
The CVE-2022-36557 vulnerability represents a critical arbitrary file upload flaw in Seiko SkyBridge MB-A100/A110 devices running firmware versions v4.2.0 and earlier. This vulnerability resides within the restore backup function of the device's web interface, creating a pathway for remote code execution through malicious file uploads. The flaw stems from insufficient input validation and file type checking mechanisms that fail to properly sanitize user-supplied files during the backup restoration process.
This vulnerability aligns with CWE-434 which describes insecure file upload vulnerabilities where applications accept files without proper validation of their content or type. The attack vector specifically targets the device's backup restoration functionality, which typically expects legitimate backup files but fails to verify that uploaded content conforms to expected file formats. An attacker can craft a malicious HTML file containing embedded malicious scripts or executable code that gets processed during the restoration procedure, effectively bypassing normal security boundaries.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with persistent access to the device's underlying system. Once successful, the vulnerability enables remote attackers to gain unauthorized access to the device's file system, potentially allowing for complete system compromise. The restored malicious file can contain javascript payloads that execute in the context of the device's web interface, or more dangerously, could include binary executables that run with elevated privileges. This creates a persistent backdoor that can be used for data exfiltration, lateral movement, or as a foothold for further attacks within the network.
From an ATT&CK framework perspective, this vulnerability maps to T1059.007 for command and scripting interpreter execution and T1566 for phishing with malicious attachments. The threat actor can leverage this vulnerability to establish initial access through a crafted backup file that appears legitimate to the device's restoration process. The attack chain typically involves uploading a malicious HTML file through the web interface, which then gets processed during the backup restoration, ultimately executing code on the target device. Organizations using these devices face significant risk as the vulnerability affects the device's core functionality and provides attackers with a direct path to system compromise.
Mitigation strategies should focus on immediate firmware updates to versions that address this vulnerability, as well as implementing network segmentation to limit access to the device's web interface. Network-based intrusion detection systems should be configured to monitor for unusual file upload activities and suspicious backup restoration attempts. Additionally, administrators should disable unnecessary backup restoration functionality when not actively required, implement strict file type validation for all uploaded content, and conduct regular security assessments to identify similar vulnerabilities in other networked devices. The vulnerability demonstrates the critical importance of validating all user-supplied content and implementing defense-in-depth strategies to protect against arbitrary file upload attacks that can lead to complete system compromise.