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.
A DLL hijacking vulnerability exists in the BIG-IP Edge Client for Windows. User interaction and administrative privileges are required to exploit this vulnerability because the victim user needs to run the executable on the system and the attacker requires administrative privileges for modifying the files in the trusted search path.
On version 14.1.x before 14.1.5.3, and all versions of 13.1.x, when the BIG-IP APM system is configured with all the following elements, undisclosed requests may cause the Traffic Management Microkernel (TMM) to terminate:
An OAuth Server that references an OAuth Provider An OAuth profile with the Authorization Endpoint set to '/' An access profile that references the above OAuth profile and is associated with an HTTPS virtual server
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
A DLL hijacking vulnerability exists in the BIG-IP Edge Client Windows Installer.
An open redirect vulnerability exists on virtual servers enabled with a BIG-IP APM access policy. This vulnerability allows an unauthenticated malicious attacker to build an open redirect URI.
In the pre connection stage, an improper enforcement of message integrity vulnerability exists in BIG-IP Edge Client for Windows and Mac OS.
An improper certificate validation vulnerability exists in BIG-IP Edge Client for Windows and macOS and may allow an attacker to impersonate a BIG-IP APM system.
A DLL hijacking vulnerability exists in the BIG-IP Edge Client Windows Installer.
An insufficient verification of data vulnerability exists in BIG-IP Edge Client Installer on macOS that may allow an attacker elevation of privileges during the installation process.
An insufficient verification of data vulnerability exists in BIG-IP Edge Client for Windows and macOS that may allow an attacker to modify its configured server list.
The BIG-IP Edge Client Installer on macOS does not follow best practices for elevating privileges during the installation process.
The BIG-IP Edge Client Installer on macOS does not follow best practices for elevating privileges during the installation process.
A DLL hijacking vulnerability exists in the BIG-IP Edge Client for Windows. User interaction and administrative privileges are required to exploit this vulnerability because the victim user needs to run the executable on the system and the attacker requires administrative privileges for modifying the files in the trusted search path.
An insufficient verification of data vulnerability exists in BIG-IP Edge Client Installer on macOS that may allow an attacker elevation of privileges during the installation process.
An insufficient verification of data vulnerability exists in BIG-IP Edge Client for Windows and macOS that may allow an attacker to modify its configured server list.
The BIG-IP Edge Client Installer on macOS does not follow best practices for elevating privileges during the installation process.
The BIG-IP Edge Client Installer on macOS does not follow best practices for elevating privileges during the installation process.
In the pre connection stage, an improper enforcement of message integrity vulnerability exists in BIG-IP Edge Client for Windows and Mac OS.
An improper certificate validation vulnerability exists in BIG-IP Edge Client for Windows and macOS and may allow an attacker to impersonate a BIG-IP APM system.
An open redirect vulnerability exists on virtual servers enabled with a BIG-IP APM access policy. This vulnerability allows an unauthenticated malicious attacker to build an open redirect URI.
When the BIG-IP APM system is configured with all the following elements, undisclosed requests may cause the Traffic Management Microkernel (TMM) to terminate: