CVE-2019-9642 in Pydio
Summary
by MITRE
An issue was discovered in proxy.php in pydio-core in Pydio through 8.2.2. Through an unauthenticated request, it possible to evaluate malicious PHP code by placing it on the fourth line of a .php file, as demonstrated by a PoC.php created by the guest account, with execution via a proxy.php?hash=../../../../../var/lib/pydio/data/personal/guest/PoC.php request. This is related to plugins/action.share/src/Store/ShareStore.php.
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Analysis
by VulDB Data Team • 06/20/2020
This vulnerability exists in the pydio-core component of Pydio versions through 8.2.2 where proxy.php fails to properly validate file paths during remote code execution attempts. The flaw allows unauthenticated attackers to execute arbitrary PHP code by leveraging a specific file placement technique that bypasses normal access controls. The vulnerability specifically targets the plugins/action.share/src/Store/ShareStore.php component which handles shared file storage operations, creating a dangerous attack vector through the proxy.php interface that processes requests with user-supplied hash parameters.
The technical implementation of this vulnerability exploits a path traversal weakness combined with inadequate input sanitization in the proxy.php script. When a malicious user creates a PHP file with executable code on the fourth line and accesses it through the proxy.php endpoint with a crafted hash parameter, the system fails to properly validate the file path and executes the embedded code. This represents a classic path traversal vulnerability that allows attackers to access files outside of the intended directory structure, specifically targeting the personal data directory of guest accounts where the malicious file is placed.
The operational impact of this vulnerability is significant as it enables remote code execution without authentication, allowing attackers to execute arbitrary commands on the affected server. The vulnerability is particularly dangerous because it leverages the guest account's permissions to create malicious files and then execute them through the proxy.php interface, effectively bypassing normal authentication mechanisms. This creates a persistent threat vector that could allow attackers to gain full control of the server, install backdoors, exfiltrate data, or use the compromised system as a launchpad for further attacks within the network infrastructure.
Organizations using Pydio versions up to 8.2.2 should immediately implement multiple layers of mitigation including network-level restrictions on access to proxy.php endpoints, mandatory authentication for all file operations, and comprehensive file path validation. The vulnerability aligns with CWE-22 Path Traversal and CWE-94 Code Injection categories, and represents a technique that could be categorized under ATT&CK tactic TA0002 Execution and TA0006 Credential Access. System administrators should also consider implementing web application firewalls to detect and block suspicious hash parameter patterns, regularly audit file permissions in personal data directories, and ensure that all Pydio installations are updated to versions that have patched this vulnerability. Additionally, monitoring for unauthorized file creation in shared storage areas and implementing least privilege principles for guest accounts can significantly reduce the attack surface exposed by this vulnerability.