CVE-2023-7079 in wrangler
Summary
by MITRE • 12/29/2023
Sending specially crafted HTTP requests and inspector messages to Wrangler's dev server could result in any file on the user's computer being accessible over the local network. An attacker that could trick any user on the local network into opening a malicious website could also read any file.
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Analysis
by VulDB Data Team • 01/21/2024
The vulnerability identified as CVE-2023-7079 represents a critical access control flaw within Cloudflare's Wrangler development server implementation. This issue stems from improper validation of HTTP request parameters and inspector messages that are processed by the local development environment. The flaw allows an attacker to exploit the dev server's configuration to gain unauthorized access to any file within the user's local file system through network-based attacks. The vulnerability specifically affects the local development server functionality that Wrangler provides for cloudflare workers development, creating a dangerous attack surface when the development server is running on a user's machine.
The technical implementation of this vulnerability involves the improper handling of file paths and request parsing within the dev server's HTTP processing pipeline. When the server receives specially crafted HTTP requests or inspector messages, it fails to properly sanitize or validate the input parameters that specify file locations. This lack of input validation creates a path traversal condition that can be exploited to access files beyond the intended scope of the development environment. The flaw is particularly dangerous because it operates at the file system level, allowing attackers to read any file that the user account running the dev server has access to, including configuration files, source code, and potentially sensitive data.
From an operational perspective, this vulnerability creates a significant risk for developers who run Wrangler's dev server in their local environments. The attack requires only that an attacker can send requests to the local network interface where the dev server is running, which is often easily achievable in local network environments. The impact extends beyond simple data exposure as attackers could potentially read sensitive configuration files, access development credentials, or discover internal application logic that might reveal additional attack vectors. The vulnerability is particularly concerning in corporate environments where developers may have elevated privileges or access to sensitive data through their development workstations.
Security professionals should consider this vulnerability in the context of CWE-22 Path Traversal and CWE-79 Cross-Site Scripting attacks as it combines elements of both file system access control failures and web application input validation issues. The attack vector aligns with ATT&CK technique T1059 Command and Scripting Interpreter and T1068 Exploitation for Privilege Escalation. Organizations should immediately address this vulnerability by ensuring that Wrangler development servers are not exposed to untrusted networks, implementing proper network segmentation, and disabling the development server when not actively in use. Additionally, developers should be educated about the risks of running development servers on local networks and the importance of proper network configuration to prevent unauthorized access to local file systems through the development environment.