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.

A flaw was discovered in Wildfly's EJB Client as shipped with Red Hat JBoss EAP 7, where some specific EJB transaction objects may get accumulated over the time and can cause services to slow down and eventaully unavailable. An attacker can take advantage and cause denial of service attack and make services unavailable.

A vulnerability was found in Wildfly's EJB where SessionOpenInvocations may not be removed properly after a response is received after a response is received causing Denial of Service.

Graeme Colman of Red Hat reported a sensitive data exposure flaw in Apache Zookeeper. An admin user's password appeared in plaintext in binary log files. A local user could read this information and use it to gain administrative access to the application.

Update 2018-08-06:

JBoss Fuse did not enable encrypted passwords by default in its usage of Apache Zookeeper. This permitted sensitive information disclosure via logging to local users. This issue is a vulnerability in JBoss Fuse's usage of Apache Zookeeper, not in Zookeeper itself as was previously stated.

A flaw was found in the Java logging library Apache Log4j in version 1.x . This allows a remote attacker to execute code on the server if the deployed application is configured to use JMSAppender.

In 1.x you will find that there are two places where lookups are done - that is JMSAppender.java:207 and JMSAppender.java:222 - if you set TopicBindingName or TopicConnectionFactoryBindingName to something that JNDI can handle - for example "ldap://host:port/a" JNDI will do exactly the same thing it does for 2.x - so 1.x is vulnerable, just attack vector is "safer" as it depends on configuration rather than user input

This flaw in Log4j 2.x is tracked via CVE-2021-44228

It was discovered that when using Digest authentication, the server does not ensure that the value of the URI in the authorization header matches the URI in the HTTP request line. This allows the attacker to execute a MITM attack and access the desired content on the server.

It was found that a flaw in commons-collection library allowed remote code execution wherever deserialization occurs. While JBoss doesnt expose the JMXInvokerServlet by default, other interfaces where deserialization occur might be vulnerable.

Note: classes directly referenced by this flaw: InvokerTransformer, InstantiateFactory, and InstantiateTransformer

External References:

http://foxglovesecurity.com/2015/11/06/what-do-weblogic-websphere-jboss-jenkins-opennms-and-your-application-have-in-common-this-vulnerability/ https://access.redhat.com/solutions/2045023

A flaw was found in xnio. A file descriptor leak caused by growing amounts of NIO Selector file, handled between garbage collection cycles, may allow the attacker to cause a denial of service. The highest threat from this vulnerability is to system availability.

A vulnerability was found in the Undertow HTTP server in versions before 2.0.28.SP1 when listening on HTTPS. An attacker can target the HTTPS port to carry out a Denial Of Service (DOS) to make the service unavailable on SSL.

A flaw was found in all undertow-2.x.x SP1 versions prior to undertow-2.0.30.SP1, all undertow-1.x.x and undertow-2.x.x versions prior to undertow-2.1.0.Final, where the Servlet container causes servletPath to normalize incorrectly by truncating the path after semicolon which may lead to an application mapping resulting in the security bypass.