CVE-2013-6880 in FlashCanvas
Summary
by MITRE
Open redirect in proxy.php in FlashCanvas before 1.6 allows remote attackers to redirect users to arbitrary web sites and conduct cross-site scripting (XSS) attacks via the HTTP Referer header.
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Analysis
by VulDB Data Team • 02/26/2024
The vulnerability identified as CVE-2013-6880 represents a critical security flaw in FlashCanvas versions prior to 1.6, specifically within the proxy.php component. This issue manifests as an open redirect vulnerability that enables remote attackers to manipulate user navigation to arbitrary web destinations. The vulnerability is particularly concerning because it leverages the HTTP Referer header as its attack vector, making it difficult to detect and prevent through standard security measures. The flaw exists in the proxy implementation that processes user requests and redirects them to external resources, creating a pathway for malicious actors to exploit the system's trust in referer-based redirection mechanisms.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization within the proxy.php script. When the system receives requests through the HTTP Referer header, it fails to properly validate or sanitize the redirect targets, allowing attackers to inject malicious URLs that will be processed as legitimate redirects. This creates a dangerous condition where user browsers are automatically redirected to attacker-controlled domains without proper verification. The vulnerability is classified under CWE-601 as an open redirect vulnerability, which is a well-documented weakness in web application security that allows attackers to redirect users to malicious sites. The flaw specifically affects the proxy functionality that is designed to handle cross-domain requests, making it a critical component in web applications that rely on FlashCanvas for canvas rendering capabilities.
The operational impact of this vulnerability extends beyond simple redirection, as it provides attackers with a foundation for conducting more sophisticated attacks including cross-site scripting (XSS) exploitation. When users are redirected to malicious sites through the open redirect, they may unknowingly interact with attacker-controlled content that can execute malicious scripts in their browser context. This creates a significant risk for users who may be logged into sensitive applications, as the malicious sites can potentially capture session cookies, credentials, or other sensitive information. The vulnerability is particularly dangerous in enterprise environments where users may access multiple applications through the same proxy infrastructure, potentially allowing attackers to escalate their attacks across different systems and applications. This aligns with ATT&CK technique T1566 which describes social engineering tactics that leverage open redirect vulnerabilities to deliver malicious payloads.
The exploitation of CVE-2013-6880 requires minimal technical skill and can be automated, making it a preferred target for attackers seeking to conduct large-scale campaigns. Attackers can craft malicious referer headers that point to phishing sites or malicious code repositories, leveraging the trust that browsers place in referer-based redirects. The vulnerability is particularly dangerous because it can be combined with other attack vectors such as phishing emails or compromised websites that direct traffic through the vulnerable proxy. Organizations using FlashCanvas versions before 1.6 are at significant risk of user compromise, as the vulnerability can be exploited without requiring any special privileges or complex attack infrastructure. The remediation process requires immediate patching of the FlashCanvas component to version 1.6 or later, which includes proper input validation and sanitization of redirect parameters. Additionally, organizations should implement proper referer validation at the network level and consider implementing additional security controls such as content security policies and web application firewalls to prevent exploitation of similar vulnerabilities in other components of their infrastructure.