Source: security@huntr.dev
Cross-site Scripting (XSS) - Stored in GitHub repository usememos/memos prior to 0.9.1.
Stored Cross-Site Scripting (XSS) vulnerabilities in the usememos/memos application allow attackers to inject malicious JavaScript code into the application. This can lead to account compromise, data theft, and session hijacking for users accessing the application. Successful exploitation requires no special privileges, making it a high-risk vulnerability.
Step 1: Payload Delivery: An attacker crafts a malicious JavaScript payload (e.g., <script>alert('XSS')</script>) and submits it as a memo within the usememos/memos application.
Step 2: Data Storage: The application stores the attacker's crafted payload in its database without proper sanitization or encoding.
Step 3: User Interaction: A legitimate user views the memo containing the malicious payload.
Step 4: Payload Execution: The browser renders the memo content, including the attacker's JavaScript payload. The browser then executes the injected JavaScript code, leading to the XSS vulnerability.
Step 5: Exploitation: The injected JavaScript can perform various malicious actions, such as stealing user cookies, redirecting users to phishing sites, or defacing the application.
The vulnerability stems from insufficient input validation and output encoding within the usememos/memos application. Specifically, user-supplied data, such as memo content, is not properly sanitized before being stored in the database and subsequently displayed to other users. This allows an attacker to inject malicious JavaScript code within the memo content. When other users view the memo, the browser executes the injected script, leading to the XSS vulnerability. The root cause is a failure to implement proper input validation to filter out potentially harmful characters and a lack of output encoding (e.g., HTML entity encoding) to prevent the browser from interpreting the injected code as legitimate HTML.
While no specific APTs are directly linked to this specific CVE, XSS vulnerabilities are commonly used by various threat actors. This type of vulnerability is often used in the initial stages of an attack to gain a foothold. Not listed on CISA KEV but should be considered a high-priority vulnerability due to its ease of exploitation and potential impact.
Network traffic analysis: Look for unusual JavaScript code being served from the application.
Web application firewall (WAF) logs: Monitor for XSS attack signatures in HTTP requests and responses.
Content Security Policy (CSP) violations: Check for CSP violations in browser developer tools, indicating the execution of unauthorized scripts.
Server-side logging: Review server logs for suspicious user input, especially within memo content.
Vulnerability Scanners: Utilize vulnerability scanners to identify the presence of the vulnerability.
Upgrade to usememos/memos version 0.9.1 or later.
Implement proper input validation to sanitize user-supplied data, filtering out potentially harmful characters and scripts.
Implement output encoding (e.g., HTML entity encoding) to prevent the browser from interpreting user-supplied data as executable code.
Implement a Content Security Policy (CSP) to restrict the execution of JavaScript from untrusted sources.
Regularly scan the application for vulnerabilities using automated tools.
Implement a Web Application Firewall (WAF) to filter malicious requests.