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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2021.3284 Netty vulnerability CVE-2021-21295 5 October 2021 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: F5 BIG-IQ Centralized Management Publisher: F5 Networks Operating System: Network Appliance Impact/Access: Provide Misleading Information -- Existing Account Reduced Security -- Existing Account Resolution: None CVE Names: CVE-2021-21295 Reference: ESB-2021.3256 ESB-2021.3208 ESB-2021.1781 ESB-2021.1144 Original Bulletin: https://support.f5.com/csp/article/K55834441 - --------------------------BEGIN INCLUDED TEXT-------------------- K55834441: Netty vulnerability CVE-2021-21295 Original Publication Date: 02 Oct, 2021 Security Advisory Description Netty is an open-source, asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients. In Netty (io.netty:netty-codec-http2) before version 4.1.60.Final there is a vulnerability that enables request smuggling. If a Content-Length header is present in the original HTTP/2 request, the field is not validated by `Http2MultiplexHandler` as it is propagated up. This is fine as long as the request is not proxied through as HTTP/1.1. If the request comes in as an HTTP/2 stream, gets converted into the HTTP/1.1 domain objects (`HttpRequest`, `HttpContent`, etc.) via `Http2StreamFrameToHttpObjectCodec `and then sent up to the child channel's pipeline and proxied through a remote peer as HTTP/1.1 this may result in request smuggling. In a proxy case, users may assume the content-length is validated somehow, which is not the case. If the request is forwarded to a backend channel that is a HTTP/1.1 connection, the Content-Length now has meaning and needs to be checked. An attacker can smuggle requests inside the body as it gets downgraded from HTTP/2 to HTTP/1.1. For an example attack refer to the linked GitHub Advisory. Users are only affected if all of this is true: `HTTP2MultiplexCodec` or `Http2FrameCodec` is used, `Http2StreamFrameToHttpObjectCodec` is used to convert to HTTP/1.1 objects, and these HTTP/1.1 objects are forwarded to another remote peer. This has been patched in 4.1.60.Final As a workaround, the user can do the validation by themselves by implementing a custom `ChannelInboundHandler` that is put in the `ChannelPipeline` behind `Http2StreamFrameToHttpObjectCodec`. ( CVE-2021-21295) Impact This vulnerability may result in HTTP request smuggling. When malformed or abnormal HTTP requests are interpreted by one or more entities in the data flow between the user and the web server, such as a proxy or firewall, they can be interpreted inconsistently, allowing the attacker to "smuggle" a request to one device without the other device being aware of it. Security Advisory Status F5 Product Development has assigned ID 1046909 (BIG-IQ) 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. Note: After a fix is introduced for a given minor branch, that fix applies to all subsequent maintenance and point releases for that branch, and no additional fixes for that branch will be listed in the table. For example, when a fix is introduced in 14.1.2.3, the fix also applies to 14.1.2.4, and all later 14.1.x releases (14.1.3.x., 14.1.4.x). For more information, refer to K51812227: Understanding security advisory versioning. Additionally, software versions preceding those listed in the Applies to (see versions) box of this article have reached the End of Technical Support (EoTS) phase of their lifecycle and are no longer evaluated for security issues. For more information, refer to the Security hotfixes section of K4602: Overview of the F5 security vulnerability response policy. +-----------+------+-----------+----------+----------+------+----------------------------+ | | |Versions |Fixes | |CVSSv3| | |Product |Branch|known to be|introduced|Severity |score^|Vulnerable component or | | | |vulnerable^|in | |2 |feature | | | |1 | | | | | +-----------+------+-----------+----------+----------+------+----------------------------+ | |16.x |None |Not | | | | | | | |applicable| | | | | +------+-----------+----------+ | | | | |15.x |None |Not | | | | | | | |applicable| | | | | +------+-----------+----------+ | | | | |14.x |None |Not | | | | |BIG-IP (all| | |applicable|Not | | | |modules) +------+-----------+----------+vulnerable|None |None | | |13.x |None |Not | | | | | | | |applicable| | | | | +------+-----------+----------+ | | | | |12.x |None |Not | | | | | | | |applicable| | | | | +------+-----------+----------+ | | | | |11.x |None |Not | | | | | | | |applicable| | | | +-----------+------+-----------+----------+----------+------+----------------------------+ | |8.x |8.0.0 - |None | | | | | | |8.1.0 | | | | | |BIG-IQ +------+-----------+----------+ | |Netty | |Centralized|7.x |7.0.0 - |None |Medium |5.3 |(io.netty:netty-codec-http2)| |Management | |7.1.0 | | | | | | +------+-----------+----------+ | | | | |6.x |6.1.0 |None | | | | +-----------+------+-----------+----------+----------+------+----------------------------+ |F5OS |1.x |None |Not |Not |None |None | | | | |applicable|vulnerable| | | +-----------+------+-----------+----------+----------+------+----------------------------+ |Traffix SDC|5.x |None |Not |Not |None |None | | | | |applicable|vulnerable| | | +-----------+------+-----------+----------+----------+------+----------------------------+ ^1F5 evaluates only software versions that have not yet reached the End of Technical Support (EoTS) phase of their lifecycle. ^2The CVSSv3 score link takes you to a resource outside of AskF5, and it is possible that the document may be removed without our knowledge. Recommended Actions If you are running a version listed in the Versions known to be vulnerable column, you can eliminate this vulnerability by installing a version listed in the Fixes introduced in column. If the Fixes introduced in column does not list a version for your branch, then no update candidate currently exists for that branch and F5 recommends upgrading to a version with the fix (refer to the table). If the Fixes introduced in column lists a version prior to the one you are running, in the same branch, then your version should have the fix. Mitigation None Supplemental Information 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 K8986: F5 software lifecycle policy o K9502: BIG-IP hotfix and point release matrix o K15106: Managing BIG-IQ product hotfixes o K15113: BIG-IQ hotfix and point release matrix 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. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: https://www.auscert.org.au/bulletins/ =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). 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