CVE-2020-28646 in ownCloud Client
Summary
by MITRE • 02/26/2021
ownCloud owncloud/client before 2.7 allows DLL Injection. The desktop client loaded development plugins from certain directories when they were present.
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Analysis
by VulDB Data Team • 03/05/2021
The vulnerability identified as CVE-2020-28646 affects ownCloud client versions prior to 2.7, representing a critical security flaw that enables malicious actors to execute arbitrary code through dynamic link library injection. This vulnerability stems from the desktop client's improper handling of plugin loading mechanisms, specifically when development plugins are present in designated directories. The flaw creates an attack vector where adversaries can manipulate the client's plugin execution flow to load malicious DLLs, thereby compromising the integrity of the affected system. The issue manifests when the client processes plugin directories without proper validation of plugin authenticity or source verification, allowing unauthorized code execution.
The technical implementation of this vulnerability aligns with CWE-427 Uncontrolled Search Path Element, where the client's search path for plugins is not properly sanitized or secured. The desktop client's plugin loading mechanism fails to implement proper access controls and validation checks, enabling attackers to place malicious DLL files in directories that the client automatically scans. This behavior represents a classic privilege escalation vulnerability where a standard user can potentially elevate privileges through code injection. The vulnerability exists because the client does not distinguish between legitimate development plugins and maliciously crafted DLL files, creating a pathway for persistent threat actors to maintain access to compromised systems.
From an operational perspective, this vulnerability poses significant risks to organizations using ownCloud client software for file synchronization and collaboration. Attackers exploiting this flaw can execute malicious code with the privileges of the logged-in user, potentially leading to data exfiltration, system compromise, or lateral movement within network environments. The impact extends beyond individual user accounts as compromised clients can serve as entry points for broader network infiltration. The vulnerability affects desktop environments where users have local access to the client installation directories, making it particularly dangerous in enterprise settings where users may have elevated privileges or where the client runs with administrative rights. Security monitoring becomes challenging as the malicious activity can appear as legitimate plugin execution, complicating detection and incident response efforts.
Mitigation strategies for CVE-2020-28646 require immediate patching of affected ownCloud client installations to version 2.7 or later, which addresses the improper plugin loading behavior through enhanced validation and access control mechanisms. Organizations should implement strict access controls on client installation directories, ensuring that only authorized personnel can modify plugin locations. The solution involves configuring the client to load plugins exclusively from trusted directories and implementing digital signature verification for all loaded modules. Additionally, network segmentation and monitoring should be enhanced to detect unusual plugin loading patterns, as outlined in the ATT&CK framework's T1059.001 technique for Command and Scripting Interpreter. System administrators should also consider implementing application whitelisting policies and regular security audits of plugin directories to prevent unauthorized modifications. The vulnerability demonstrates the importance of secure coding practices and proper input validation, particularly when handling dynamic module loading scenarios that could be exploited by threat actors seeking persistent access to target systems.