NetScaler WAF Signatures Update v123

NetScaler has released a new version of its integrated Web App Firewall signatures to help customers mitigate several CVEs with variable CVSS. Two notable additions are:

CVE-2024-21650 which is a vulnerability in XWiki Enterprise, an open-source wiki software that is used by many organizations to manage their knowledge base. This vulnerability has been assigned a CVSS score of 9.8, which is considered critical. The vulnerability allows an attacker to execute arbitrary code with elevated privileges, which could lead to a complete compromise of the system. This could result in the loss of sensitive data, unauthorized access to critical systems, and other serious consequences. It is recommended that users apply the latest security patches to their XWiki Enterprise installations to mitigate the risk of exploitation.

CVE-2023-22527 which is a template injection vulnerability in Atlassian Confluence Data Center and Server. This vulnerability only affects out-of-date versions of these products. An unauthenticated attacker could exploit this vulnerability by sending a specially crafted request to a vulnerable Confluence Data Center or Server instance. Successful exploitation would allow an attacker to obtain remote code execution. This vulnerability carries a CVSS score of 10, the highest critical rating. It is recommended that users upgrade to the latest version of Confluence Data Center or Server to mitigate the risk of exploitation. Additionally, users should ensure that their Confluence instances are not exposed to the internet and that access to the application is restricted to authorized personnel only.

 Signatures included in v123:

NetScaler customers can quickly import the above signatures to help reduce risk and lower exposure associated with these vulnerabilities. Signatures are compatible with NetScaler (formerly Citrix ADC) software version 11.1, 12.0, 12.1, 13.0 and 13.1. NOTE: Software versions 11.1 and 12.0 are end of life, and you should consider upgrading for continued support. Learn more about the NetScaler software release lifecycle.

If you are already using NetScaler Web App Firewall with the signature auto-update feature enabled, verify that your signature file version is 123 or later and then follow these steps.

1. Search your signatures for <number>
2. Select the results with ID 
3. Choose “Enable Rules” and click OK

NetScaler WAF Best Practices

NetScaler recommends that WAF users always download the latest signature version, enable signature auto-update, and subscribe to receive signature alert notifications. NetScaler will continue to monitor this dynamic situation and provide updates as new mitigations become available.

Handling false positives

If app availability is affected by false positives that result from the above mitigation policies, relaxations can be applied. NetScaler recommends the following modifications to the policy.

Modifications to NetScaler Web App Firewall Policy:

add policy patset exception_list

# (Example: bind policy patset exception_list “/exception_url”) 

Prepend the existing WAF policy with:

HTTP.REQ.URL.CONTAINS_ANY(“exception_list”).NOT

# (Example :  set appfw policy my_WAF_policy q^HTTP.REQ.URL.CONTAINS_ANY(“exception_list”).NOT && <existing rule>^

NOTE: Any endpoint covered by the exception_list may expose those assets to risks 

Additional Information

NetScaler Web App Firewall benefits from a single code base across all its form-factors (physical, virtual, bare-metal, and containers). This signature update applies to all form factors and deployment models of NetScaler Web App Firewall.

Learn more about NetScaler Web app Firewall, read our alert articles and bot signature articles to learn more about NetScaler WAF signatures, and find out how you can receive signature alert notifications.

Please join the NetScaler Community today and engage with your peers to learn more about how they are protecting their businesses with NetScaler WAF.