Finding and Fixing Vulnerabilities in Cross Site Scripting , a High Risk Vulnerability

With Notes on Remediation, Penetration Testing, Disclosures, Patching and Exploits

Contents

  • Vital information on this issue
  • Scanning For and Finding Vulnerabilities in Cross Site Scripting
  • Penetration Testing (Pentest) for this Vulnerability
  • Security updates on Cross Site Scripting
  • Disclosures related to Vulnerabilities in Cross Site Scripting
  • Confirming the Presence of Vulnerabilities in Cross Site Scripting
  • False positive/negatives
  • Patching/Repairing this vulnerability
  • Exploits related to Vulnerabilities in Cross Site Scripting

Vital Information on This Issue
Vulnerabilities in Cross Site Scripting is a high risk vulnerability that is one of the most frequently found on networks around the world. This issue has been around since at least 1990 but has proven either difficult to detect, difficult to resolve or prone to being overlooked entirely.


Vulnerability Name: Vulnerabilities in Cross Site Scripting
Test ID: 601
Risk: High
Category: Server Side Scripts
Type: Attack
Summary: The scripts listed below are vulnerable to a "Cross Site Scripting" attack. Next to each script, there is a description of the type of attack that is possible, and a way to recreate the attack. If the attack is a simple HTTP GET request, you can usually paste it into your browser to see how it works. If it's a POST attack, the parameters for the POST request will be listed in square parenthesis. Note that the way to validate a Cross-Site-Scripting attack is by seeing the text that returns from the server includes the attack (without filtering). Even if the attack does not trigger a script on the browser side, it is still most likely dangerous, since it could be made exploitable by relatively minor tweaks to the attack. Consider this a Proof-of-Concept only.
Impact: A Cross-Site-Scripting attack may be used by attackers to bypass access controls such as the same origin policy. Their effect may range from a petty nuisance to a significant security risk, depending on the sensitivity of the data handled by the vulnerable site and the nature of any security mitigation implemented by the site's owner.
Solution: Filter user input to discard characters such as < and >. Make sure your server does not display error messages that contain input received from the user.
CVE: CVE-2012-4178
More Information: https://www.exploit-db.com/exploits/20123/
http://seclists.org/fulldisclosure/2015/Nov/104
Nist NVD (CVSS): CVE-2012-2574
CVSS Score: 7.5
For more information on this also issue see: www.securiteam.com

Scanning For and Finding Vulnerabilities in Cross Site Scripting
Use of Vulnerability Management tools, like AVDS, are standard practice for the discovery of this vulnerability. The primary failure of VA in finding this vulnerability is related to setting the proper scope and frequency of network scans. It is vital that the broadest range of hosts (active IPs) possible are scanned and that scanning is done frequently. We recommend weekly. Your existing scanning solution or set of test tools should make this not just possible, but easy and affordable. If that is not the case, please consider AVDS.

Penetration Testing (pentest) for this Vulnerability
The Vulnerabilities in Cross Site Scripting is prone to false positive reports by most vulnerability assessment solutions. AVDS is alone in using behavior based testing that eliminates this issue. For all other VA tools security consultants will recommend confirmation by direct observation. In any case Penetration testing procedures for discovery of Vulnerabilities in Cross Site Scripting produces the highest discovery accuracy rate, but the infrequency of this expensive form of testing degrades its value. The ideal would be to have pentesting accuracy and the frequency and scope possibilities of VA solutions, and this is accomplished only by AVDS.

Security Updates on Vulnerabilities in Cross Site Scripting
For the most current updates on this vulnerability please check www.securiteam.com Given that this is one of the most frequently found vulnerabilities, there is ample information regarding mitigation online and very good reason to get it fixed. Hackers are also aware that this is a frequently found vulnerability and so its discovery and repair is that much more important. It is so well known and common that any network that has it present and unmitigated indicates "low hanging fruit" to attackers.

Disclosures related to this vulnerability

Confirming the Presence of Vulnerabilities in Cross Site Scripting
AVDS is currently testing for and finding this vulnerability with zero false positives. If your current set of tools is indicating that it is present but you think it is probably a false positive, please contact us for a demonstration of AVDS.

False positive/negatives
The secret killer of VA solution value is the false positive. There was an industry wide race to find the most vulnerabilities, including Vulnerabilities in Cross Site Scripting ,and this resulted in benefit to poorly written tests that beef up scan reports by adding a high percentage of uncertainty. This may have sold a lot of systems some years ago, but it also stuck almost all VA solutions with deliberately inaccurate reporting that adds time to repairs that no administrator can afford. Beyond Security did not participate in this race to mutually assured destruction of the industry and to this day produces the most accurate and actionable reports available.

Patching/Repairing this Vulnerability
http://www.xssed.com/article/17/Paper_How_to_Fix_a_XSS_Vulnerability_in_PHP_Source_Codes/ Vulnerabilities in Cross Site Scripting is a high risk vulnerability that is also high frequency and high visibility. This is the most severe combination of security factors that exists and it is extremely important to find it on your network and fix it as soon as possible.

Exploits related to Vulnerabilities in Cross Site Scripting
Stored XSS
Reflected XSS
DOM-based XSS

Please also visit www.securiteam.com to view any exploits available for this vulnerability, or search using "Vulnerabilities in Cross Site Scripting".


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