CVE-2021-44537 in ownCloud
Summary
by MITRE • 01/16/2022
ownCloud owncloud/client before 2.9.2 allows Resource Injection by a server into the desktop client via a URL, leading to remote code execution.
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Analysis
by VulDB Data Team • 01/19/2022
The vulnerability identified as CVE-2021-44537 affects ownCloud client versions prior to 2.9.2 and represents a critical resource injection flaw that enables remote code execution through manipulated server responses. This vulnerability stems from insufficient input validation and sanitization within the desktop client application when processing URLs provided by the server component. The flaw allows an attacker controlling the ownCloud server to inject malicious resources into the client environment, creating a pathway for arbitrary code execution on the victim's desktop system.
The technical implementation of this vulnerability involves the client application's handling of server-provided URLs without proper validation of their contents or origins. When the desktop client processes these URLs, it fails to adequately sanitize or verify the resource references, allowing malicious payloads to be executed within the context of the user's session. This type of vulnerability falls under CWE-94, which encompasses "Improper Control of Generation of Code" and represents a classic case of code injection where server-side modifications can influence client-side execution behavior. The vulnerability operates through the client's resource loading mechanisms, where legitimate URLs are manipulated to reference malicious content that gets executed without proper user consent or awareness.
The operational impact of CVE-2021-44537 extends beyond simple remote code execution to encompass potential privilege escalation and persistent access capabilities. An attacker exploiting this vulnerability can gain full control over the victim's desktop environment, potentially accessing sensitive data, installing additional malware, or using the compromised system as a pivot point for further network exploration. The attack vector requires the victim to be connected to an attacker-controlled ownCloud server, making this vulnerability particularly concerning in enterprise environments where centralized file synchronization is common. This vulnerability aligns with ATT&CK technique T1059.007, which covers "Command and Scripting Interpreter: PowerShell," as the malicious code execution can occur through PowerShell or similar scripting mechanisms available on Windows systems.
Mitigation strategies for CVE-2021-44537 focus primarily on immediate software updates to version 2.9.2 or later, which includes proper URL validation and resource sanitization mechanisms. Organizations should implement network segmentation to limit access to ownCloud servers and establish strict firewall rules to prevent unauthorized server access. Additionally, user education regarding the risks of connecting to untrusted ownCloud servers and monitoring for unusual client behavior can provide additional layers of protection. The vulnerability demonstrates the importance of secure coding practices in client applications and highlights the need for comprehensive input validation even for trusted server components. Security teams should also consider implementing endpoint detection and response solutions to monitor for suspicious process execution patterns that might indicate exploitation attempts.