HTTP/2 Rapid reset attack The HTTP/2 protocol allows clients to indicate to the server that a previous stream should be canceled by sending a RSTSTREAM frame. The protocol does not require the client and server to coordinate the cancellation in any way, the client may do it unilaterally. The client may also assume that the cancellation will take effect immediately when the server receives the RSTSTREAM frame, before any other data from that TCP connection is processed.

Abuse of this feature is called a Rapid Reset attack because it relies on the ability for an endpoint to send a RSTSTREAM frame immediately after sending a request frame, which makes the other endpoint start working and then rapidly resets the request. The request is canceled, but leaves the HTTP/2 connection open.

The HTTP/2 Rapid Reset attack built on this capability is simple: The client opens a large number of streams at once as in the standard HTTP/2 attack, but rather than waiting for a response to each request stream from the server or proxy, the client cancels each request immediately.

The ability to reset streams immediately allows each connection to have an indefinite number of requests in flight. By explicitly canceling the requests, the attacker never exceeds the limit on the number of concurrent open streams. The number of in-flight requests is no longer dependent on the round-trip time (RTT), but only on the available network bandwidth.

In a typical HTTP/2 server implementation, the server will still have to do significant amounts of work for canceled requests, such as allocating new stream data structures, parsing the query and doing header decompression, and mapping the URL to a resource. For reverse proxy implementations, the request may be proxied to the backend server before the RSTSTREAM frame is processed. The client on the other hand paid almost no costs for sending the requests. This creates an exploitable cost asymmetry between the server and the client.

Multiple software artifacts implementing HTTP/2 are affected. This advisory was originally ingested from the swift-nio-http2 repo advisory and their original conent follows.

swift-nio-http2 specific advisory swift-nio-http2 is vulnerable to a denial-of-service vulnerability in which a malicious client can create and then reset a large number of HTTP/2 streams in a short period of time. This causes swift-nio-http2 to commit to a large amount of expensive work which it then throws away, including creating entirely new Channels to serve the traffic. This can easily overwhelm an EventLoop and prevent it from making forward progress.

swift-nio-http2 1.28 contains a remediation for this issue that applies reset counter using a sliding window. This constrains the number of stream resets that may occur in a given window of time. Clients violating this limit will have their connections torn down. This allows clients to continue to cancel streams for legitimate reasons, while constraining malicious actors.

An authenticated SQL injection vulnerability exists in the BIG-IP Configuration utility which

may allow an authenticated attacker with network access to the Configuration utility through the BIG-IP management port and/or self IP addresses to execute arbitrary system commands.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated

F5 BIG-IP Configuration utility contains an authentication bypass using an alternate path or channel vulnerability due to undisclosed requests that may allow an unauthenticated attacker with network access to the BIG-IP system through the management port and/or self IP addresses to execute system commands. This vulnerability can be used in conjunction with CVE-2023-46748.

On specific hardware platforms, on BIG-IP versions 16.1.x before 16.1.3.1, 15.1.x before 15.1.7, 14.1.x before 14.1.5.1, and all versions of 13.1.x, while Intel QAT (QuickAssist Technology) and the AES-GCM/CCM cipher is in use, undisclosed conditions can cause BIG-IP to send data unencrypted even with an SSL Profile applied.

On an F5 BIG-IP 13.0.0-13.1.0.5, 12.1.0-12.1.3.1, or 11.2.1-11.6.3.1 system configured in Appliance mode, the TMOS Shell (tmsh) may allow an administrative user to use the dig utility to gain unauthorized access to file system resources.

On F5 BIG-IP 13.0.0-13.1.0.5 or 12.0.0-12.1.3.3, malicious root users with access to a VCMP guest can cause a disruption of service on adjacent VCMP guests running on the same host. Exploiting this vulnerability causes the vCMPd process on the adjacent VCMP guest to restart and produce a core file. This issue is only exploitable on a VCMP guest which is operating in "host-only" or "bridged" mode. VCMP guests which are "isolated" are not impacted by this issue and do not provide mechanism to exploit the vulnerability. Guests which are deployed in "Appliance Mode" may be impacted however the exploit is not possible from an Appliance Mode guest. To exploit this vulnerability root access on a guest system deployed as "host-only" or "bridged" mode is required.

On F5 BIG-IP 13.0.0-13.1.0.5, 12.1.0-12.1.3.3, or 11.2.1-11.6.3.1, administrative users by way of undisclosed methods can exploit the ssldump utility to write to arbitrary file paths. For users who do not have Advanced Shell access (for example, any user when licensed for Appliance Mode), this allows more permissive file access than intended.

On F5 BIG-IP 13.0.0-13.1.0.5, 12.1.0-12.1.2, or 11.2.1-11.6.3.1, Enterprise Manager 3.1.1, BIG-IQ Centralized Management 5.0.0-5.4.0 or 4.6.0, BIG-IQ Cloud and Orchestration 1.0.0, or F5 iWorkflow 2.0.2-2.3.0, authenticated users granted TMOS Shell (tmsh) access can access objects on the file system which would normally be disallowed by tmsh restrictions. This allows for authenticated, low privileged attackers to exfiltrate objects on the file system which should not be allowed.

On F5 BIG-IP 13.1.0-13.1.0.5, malformed TCP packets sent to a self IP address or a FastL4 virtual server may cause an interruption of service. The control plane is not exposed to this issue. This issue impacts the data plane virtual servers and self IPs.

On F5 BIG-IP 13.1.0-13.1.0.3, 13.0.0, 12.1.0-12.1.3.3, 11.6.1-11.6.3.1, 11.5.1-11.5.5, or 11.2.1, a malformed TLS handshake causes TMM to crash leading to a disruption of service. This issue is only exposed on the data plane when Proxy SSL configuration is enabled. The control plane is not impacted by this issue.

On F5 BIG-IP 13.1.0-13.1.0.5, when Large Receive Offload (LRO) and SYN cookies are enabled (default settings), undisclosed traffic patterns may cause TMM to restart.

On F5 BIG-IP 13.1.0-13.1.0.5, maliciously crafted HTTP/2 request frames can lead to denial of service. There is data plane exposure for virtual servers when the HTTP2 profile is enabled. There is no control plane exposure to this issue.

On F5 BIG-IP 13.0.0-13.1.0.5, using RADIUS authentication responses from a RADIUS server with IPv6 addresses may cause TMM to crash, leading to a failover event.

On F5 BIG-IP 13.1.0-13.1.0.3 or 13.0.0, when authenticated administrative users execute commands in the Traffic Management User Interface (TMUI), also referred to as the BIG-IP Configuration utility, restrictions on allowed commands may not be enforced.