CVE-2019-12161 in webpagetest
Summary
by MITRE
WPO WebPageTest 19.04 allows SSRF because ValidateURL in www/runtest.php does not consider octal encoding of IP addresses (such as 0300.0250 as a replacement for 192.168).
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Analysis
by VulDB Data Team • 09/21/2023
The vulnerability CVE-2019-12161 affects WPO WebPageTest version 19.04 and represents a significant server-side request forgery flaw that stems from inadequate URL validation mechanisms. This vulnerability specifically resides in the ValidateURL function within the www/runtest.php file, where the application fails to properly handle octal IP address representations that could bypass intended network restrictions. The flaw allows attackers to craft malicious URLs that appear to target external resources while actually directing requests to internal network addresses through octal encoding techniques.
The technical implementation of this vulnerability demonstrates a classic input validation weakness where the application's URL parsing logic does not adequately sanitize or normalize IP address formats before processing. When an attacker submits a URL containing an octal representation such as 0300.0250, the system should recognize this as equivalent to the decimal format 192.168.0.0 but instead processes it as a valid external address. This occurs because the validation routine does not perform proper octal-to-decimal conversion or normalization, allowing maliciously encoded IP addresses to bypass network access controls that were designed to prevent internal network scanning or unauthorized access.
The operational impact of this vulnerability extends beyond simple network reconnaissance as it could enable attackers to perform unauthorized internal network scanning, access internal services, or potentially exploit other vulnerabilities within the internal network that are not directly exposed to the internet. Attackers could leverage this flaw to target internal systems such as database servers, administrative interfaces, or other sensitive internal resources that are typically protected by network segmentation. The vulnerability essentially undermines the application's network isolation mechanisms, creating a pathway for attackers to move laterally within the network infrastructure.
From a cybersecurity framework perspective, this vulnerability aligns with CWE-917, which covers "Improper Neutralization of Special Elements used in an Expression" and specifically addresses the weakness in input validation that allows for bypassing security controls through encoding techniques. The vulnerability also maps to ATT&CK technique T1071.004, which covers "Application Layer Protocol: DNS" and represents how attackers can leverage protocol parsing weaknesses to bypass network controls. Organizations should implement comprehensive URL validation that normalizes all IP address representations to their canonical forms before processing, ensuring that octal, hexadecimal, and other encoded formats are properly converted to standard decimal notation. Additionally, network segmentation controls should be reinforced with proper firewall rules that block access to internal network ranges from external-facing applications, and input validation should include comprehensive checks for all possible IP address encoding schemes.
Mitigation strategies should focus on implementing robust URL parsing and normalization routines that explicitly convert octal IP addresses to their decimal equivalents before any validation occurs. The application should be updated to include comprehensive input sanitization that rejects or normalizes all non-standard IP address formats. Network administrators should also implement additional layers of protection including strict firewall rules that prevent access to internal network ranges from external-facing services, and regular security audits should verify that all URL processing components properly handle various IP address representations. The fix should also include logging mechanisms that can detect and alert on suspicious URL patterns that attempt to exploit encoding-based bypass techniques, providing visibility into potential exploitation attempts.