CVE-2021-41323 in Cells
Summary
by MITRE • 10/01/2021
Directory traversal in the Compress feature in Pydio Cells 2.2.9 allows remote authenticated users to overwrite personal files, or Cells files belonging to any user, via the format parameter.
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Analysis
by VulDB Data Team • 10/04/2021
The vulnerability identified as CVE-2021-41323 represents a critical directory traversal flaw within the Compress feature of Pydio Cells version 2.2.9. This issue affects the file management capabilities of the platform and stems from improper input validation in the format parameter handling mechanism. The vulnerability specifically impacts the compression functionality where users can specify archive formats, creating a potential attack vector through maliciously crafted parameters that manipulate the underlying file system paths.
The technical exploitation of this vulnerability occurs through the manipulation of the format parameter within the Compress feature, allowing authenticated users to traverse directory structures beyond their intended scope. This flaw enables attackers to access and modify files outside of their designated user directories, potentially leading to unauthorized file overwrites or modifications of system files. The vulnerability arises from insufficient sanitization of user-supplied input, particularly in how the system processes and interprets the format parameter during compression operations.
From an operational perspective, this vulnerability poses significant risks to organizations utilizing Pydio Cells 2.2.9, as it allows for arbitrary file system manipulation by authenticated users. The impact extends beyond simple file overwrites to potentially compromise system integrity and data confidentiality, as attackers could target critical system files or personal user data belonging to other users within the same system. The authenticated nature of the exploit means that attackers must first obtain valid credentials, but once achieved, they can leverage this vulnerability to cause substantial damage.
The vulnerability aligns with CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. This classification indicates that the flaw involves the system's failure to properly validate and sanitize input parameters that influence file system operations. Additionally, the vulnerability can be mapped to ATT&CK technique T1074.001, which covers data staging through the use of file systems, as the compromised system allows for unauthorized file manipulation and potential data exfiltration.
Organizations should implement immediate mitigations including updating to the latest version of Pydio Cells where this vulnerability has been addressed, implementing proper input validation and sanitization for all user-supplied parameters, and establishing strict access controls and monitoring mechanisms. The fix typically involves proper parameter validation that ensures compression format parameters do not contain directory traversal sequences or special characters that could manipulate the file system path. Network segmentation and principle of least privilege access controls should also be enforced to limit the potential impact of such vulnerabilities. Regular security assessments and code reviews focusing on input validation and file system operations should be conducted to prevent similar issues from emerging in other components of the system.