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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2020.0139 BIG-IP APM Portal Access vulnerability CVE-2020-5853 14 January 2020 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: BIG-IP APM Publisher: F5 Networks Operating System: Network Appliance Impact/Access: Cross-site Scripting -- Remote with User Interaction Resolution: Mitigation CVE Names: CVE-2020-5853 Original Bulletin: https://support.f5.com/csp/article/K73183618 - --------------------------BEGIN INCLUDED TEXT-------------------- K73183618:BIG-IP APM Portal Access vulnerability CVE-2020-5853 Security Advisory Original Publication Date: 14 Jan, 2020 Security Advisory Description In BIG-IP APM Portal Access, HTTP pages that are served by back-end servers and have special JavaScript code may cause internal name conflicts. (CVE-2020-5853) Impact BIG-IP APM An attacker who can control JavaScript code served by back-end servers may bypass the client-side rewriting that BIG-IP APM Portal Access performs and launch a cross-site scripting (XSS) attack. Security Advisory Status F5 Product Development has assigned ID 838881 (BIG-IP) to this vulnerability. To determine if your product and version have been evaluated for this vulnerability, refer to the Applies to (see versions) box. To determine if your release is known to be vulnerable, the components or features that are affected by the vulnerability, and for information about releases, point releases, or hotfixes that address the vulnerability, refer to the following table. For more information about security advisory versioning, refer to K51812227: Understanding Security Advisory versioning. +-------------------+------+----------+----------+----------+------+----------+ | | |Versions |Fixes | |CVSSv3|Vulnerable| |Product |Branch|known to |introduced|Severity |score^|component | | | |be |in | |1 |or feature| | | |vulnerable| | | | | +-------------------+------+----------+----------+----------+------+----------+ | |15.x |15.0.0 - |None | | | | | | |15.1.0 | | | | | | +------+----------+----------+ | | | | |14.x |14.0.0 - |None | | | | | | |14.1.2 | | | | | | +------+----------+----------+ | |BIG-IP APM| |BIG-IP (APM) |13.x |13.1.0 - |None |Medium |4.9 |Portal | | | |13.1.3 | | | |Access | | +------+----------+----------+ | | | | |12.x |12.1.0 - |None | | | | | | |12.1.5 | | | | | | +------+----------+----------+ | | | | |11.x |11.5.2 - |None | | | | | | |11.6.5 | | | | | +-------------------+------+----------+----------+----------+------+----------+ | |15.x |None |Not | | | | | | | |applicable| | | | | +------+----------+----------+ | | | |BIG-IP (LTM, AAM, |14.x |None |Not | | | | |AFM, Analytics, | | |applicable| | | | |ASM, DNS, Edge +------+----------+----------+ | | | |Gateway, FPS, GTM, |13.x |None |Not |Not |None |None | |Link Controller, | | |applicable|vulnerable| | | |PEM, +------+----------+----------+ | | | |WebAccelerator) |12.x |None |Not | | | | | | | |applicable| | | | | +------+----------+----------+ | | | | |11.x |None |Not | | | | | | | |applicable| | | | +-------------------+------+----------+----------+----------+------+----------+ | |7.x |None |Not | | | | | | | |applicable| | | | | +------+----------+----------+ | | | |BIG-IQ Centralized |6.x |None |Not |Not |None |None | |Management | | |applicable|vulnerable| | | | +------+----------+----------+ | | | | |5.x |None |Not | | | | | | | |applicable| | | | +-------------------+------+----------+----------+----------+------+----------+ |Traffix SDC |5.x |None |Not |Not |None |None | | | | |applicable|vulnerable| | | +-------------------+------+----------+----------+----------+------+----------+ ^1The CVSSv3 score link takes you to a resource outside of AskF5, and it is possible that the document may be removed without our knowledge. Security Advisory Recommended Actions If you are running a version listed in the Versions known to be vulnerable column, you can eliminate this vulnerability by upgrading to a version listed in the Fixes introduced in column. If the table lists only an older version than what you are currently running, or does not list a non-vulnerable version, then no upgrade candidate currently exists. Mitigation To mitigate this vulnerability, use BIG-IP APM Access Control Lists (ACLs) to restrict user access to host, port, and URL path combinations (also known as resource items) and ensure that only trusted, back-end servers serve content to the BIG-IP system and clients. To restrict user access using a BIG-IP APM ACL, perform both of the following procedures: o Create an ACL to reject all IP addresses, port numbers, and URL paths (resource items) by default o Verify that you configured all Portal Access resource items you want to allow When you finish these procedures, you: o Created your ACL. o Verified that you correctly configured your Portal Access resource items. Finally, for your ACL to take effect, you must assign it to your access policy using the Visual Policy Editor (VPE) at the appropriate branches. Important: When you assign the ACL that you created in the first procedure to your access policy, the system enforces the rules of the ACL. F5 recommends that you test your configurations to ensure they do no disrupt legitimate services and perform this procedure during a scheduled maintenance window. Create an ACL to reject all IP addresses, port numbers, and URL paths (resource items) by default Create an ACL to reject all traffic by default, and make it the last ACL in order. This action causes the system to reject traffic that you have not configured as a Portal Access resource item. To do so perform the following procedure: Impact of action: Performing the suggested procedure should not have a negative impact on your system, because the ACL does not take effect until you assign it to an access policy. Before assigning it to an access policy, F5 recommends that you first test your ACLs in a staging environment to ensure they do not disrupt legitimate services and perform this procedure during a scheduled maintenance window. 1. Log in to the Configuration utility. 2. Go to Access > Access Control Lists > User-defined ACLs. Note: For BIG-IP 12.x and earlier, go to Access Policy > ACLs. 3. Select Create. 4. In Name, enter a name for the ACL. 5. On the ACL Order list, select Last. Important: When you assign the last and largest number to this ACL, users can access your portal applications. If you specify 0 for this ACL in the ACL Order list, the system rejects all access to your applications. 6. Select Create. 7. In Access Control Entries, select Add. 8. On the Type list, select L4 + L7. 9. On the Scheme list, select any. 10. In Paths, enter asterisk (*). 11. On the Action list, select Reject. 12. Select Finished. Verify that you configured all Portal Access resource items you want to allow The ACL you created in the first procedure rejects all traffic. Before you assign it to your access policy, verify that you accurately configured any host, port, or URL path (resource item) that you want to allow. To verify that you configured resource items you want to allow, perform the following procedure: Impact of action: Performing the suggested procedure should not have a negative impact on your system. 1. Log in to the Configuration utility. 2. Go to Access > Connectivity / VPN > Portal Access > Portal Access Lists. Note: For BIG-IP 12.x and earlier, go to Access Policy > Portal Access > Portal Access List. 3. Select the name of the resource item you want to verify. 4. Under Resource Items, verify that you configured a list of host, port, and URL path combinations required for your application. The ACL you created in the first procedure rejects any host, port, or URL path that is not in this list. Acknowledgements F5 would like to acknowledge Charles d'Hondt of LEXFO Security for bringing this issue to our attention and for following the highest standards of responsible disclosure. Supplemental Information o K51812227: Understanding Security Advisory versioning o K41942608: Overview of Security Advisory articles o K4602: Overview of the F5 security vulnerability response policy o K4918: Overview of the F5 critical issue hotfix policy o K9502: BIG-IP hotfix and point release matrix o K13123: Managing BIG-IP product hotfixes (11.x - 15.x) o K167: Downloading software and firmware from F5 o K9970: Subscribing to email notifications regarding F5 products o K9957: Creating a custom RSS feed to view new and updated documents - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. 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