CVE-2020-15239 in xmpp-http-upload
Summary
by MITRE • 10/06/2020
In xmpp-http-upload before version 0.4.0, when the GET method is attacked, attackers can read files which have a `.data` suffix and which are accompanied by a JSON file with the `.meta` suffix. This can lead to Information Disclosure and in some shared-hosting scenarios also to circumvention of authentication or other limitations on the outbound (GET) traffic. For example, in a scenario where a single server has multiple instances of the application running (with separate DATA_ROOT settings), an attacker who has knowledge about the directory structure is able to read files from any other instance to which the process has read access. If instances have individual authentication (for example, HTTP authentication via a reverse proxy, source IP based filtering) or other restrictions (such as quotas), attackers may circumvent those limits in such a scenario by using the Directory Traversal to retrieve data from the other instances. If the associated XMPP server (or anyone knowing the SECRET_KEY) is malicious, they can write files outside the DATA_ROOT. The files which are written are constrained to have the `.meta` and the `.data` suffixes; the `.meta` file will contain the JSON with the Content-Type of the original request and the `.data` file will contain the payload. The issue is patched in version 0.4.0.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 11/17/2020
The vulnerability described in CVE-2020-15239 represents a critical information disclosure flaw in the xmpp-http-upload component affecting versions prior to 0.4.0. This vulnerability stems from improper input validation and directory traversal mechanisms within the HTTP file upload and retrieval system. The flaw specifically manifests when the GET method is utilized, allowing attackers to exploit a path traversal vulnerability that enables reading files with specific file extensions. The vulnerability is particularly concerning because it targets files with .data and .meta suffixes, which are part of the application's internal file handling mechanism for storing and retrieving XMPP file uploads. The .meta files contain JSON metadata including Content-Type information while .data files store the actual payload data, creating a scenario where attackers can access sensitive metadata and potentially the underlying file content through crafted requests.
The technical exploitation of this vulnerability involves leveraging directory traversal techniques to access files outside the intended data root directories. This issue becomes particularly dangerous in shared hosting environments where multiple instances of the application may be running on the same server with different DATA_ROOT configurations. The vulnerability allows attackers to read files from other instances of the application that they might not normally have access to, effectively bypassing instance-level security boundaries. This cross-instance information disclosure occurs because the application fails to properly validate file paths and does not adequately enforce separation between different application instances. The flaw enables attackers to discover and access data from other application instances that have different authentication mechanisms, IP-based restrictions, or resource quotas, creating a scenario where security controls designed to isolate instances can be circumvented.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially enable more sophisticated attacks in multi-tenant hosting scenarios. Attackers can leverage this vulnerability to gain unauthorized access to files from other application instances, potentially accessing sensitive user data, configuration information, or authentication tokens that might be stored in the .meta files. The vulnerability also has implications for authentication bypass, as attackers can retrieve data from instances that have individual authentication mechanisms such as HTTP authentication via reverse proxies or source IP filtering. This creates a scenario where attackers can effectively circumvent security controls designed to limit access to specific instances. Furthermore, if the associated XMPP server or an attacker with knowledge of the SECRET_KEY is malicious, they can not only read files but also write files outside the designated DATA_ROOT, creating a potential write-up scenario where malicious actors can inject files with the required .meta and .data extensions. The vulnerability's patch in version 0.4.0 addresses these path traversal issues through proper input validation and enhanced file access controls that prevent unauthorized access to files outside the intended data directories.
This vulnerability aligns with CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) and CWE-23 (Relative Path Traversal) categories, representing classic directory traversal flaws that have been consistently identified in web applications and file handling systems. The attack pattern follows ATT&CK technique T1078 (Valid Accounts) and T1566 (Phishing) where attackers can gain unauthorized access to system resources through exploitation of path traversal vulnerabilities. The vulnerability also relates to T1567 (Exfiltration Over Web Service) as attackers can extract sensitive data from other instances through the HTTP GET method. Organizations implementing xmpp-http-upload components should ensure proper patch management and validate that all instances are updated to version 0.4.0 or later. Additionally, security controls should include proper input validation, file path sanitization, and instance-level isolation mechanisms to prevent cross-instance data access. The vulnerability demonstrates the importance of proper access controls and input validation in multi-tenant applications where shared infrastructure may expose security boundaries if not properly enforced.