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.

In Wireshark 3.0.0 to 3.0.1, 2.6.0 to 2.6.8, and 2.4.0 to 2.4.14, the dissection engine could crash. This was addressed in epan/packet.c by restricting the number of layers and consequently limiting recursion.

A flaw was found in computer hardware of the Intel microprocessors related to the instruction-side TLB (Translation Lookaside Buffer) that caches translations from guest (and host) virtual addresses into physical addresses.

This is a software fix that attempts to prevent exploitation of the hardware through preventing a hacker from creating an exploitable condition

Additional information:

https://access.redhat.com/security/vulnerabilities/ifu-page-mce

A cross-site scripting vulnerability was discovered in bootstrap. If an attacker could control the data given to tooltip or popover, they could inject HTML or Javascript into the rendered page when tooltip or popover events fired.

On the BIG-IP system, undisclosed endpoints that contain static non-sensitive information are accessible to an unauthenticated remote attacker through the Configuration utility.

A directory traversal vulnerability exists in the BIG-IP Configuration utility that allows a highly privileged authenticated attacker to access files which are not limited to the intended files.

When running in Appliance mode, a highly privileged authenticated attacker with access to SCP and SFTP may be able to bypass Appliance mode restrictions using undisclosed commands.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Undisclosed traffic can cause the Traffic Management Microkernel (TMM) to terminate.  This issue may occur when a Datagram Transport Layer Security (DTLS) 1.2 virtual server is enabled with a Server SSL profile that is configured with a certificate, key, and the SSL Sign Hash set to ANY, and the backend server is enabled with DTLS 1.2 and client authentication.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

When a BIG-IP Advanced WAF or BIG-IP ASM Security Policy is configured with a JSON content profile that has a malformed JSON schema, and the security policy is applied to a virtual server, undisclosed requests can cause the bd process to terminate.

When the BIG-IP Advanced WAF and ASM security policy and a server-side HTTP/2 profile are configured on a virtual server, undisclosed traffic can cause the Traffic Management Microkernel (TMM) to terminate.

A vulnerability exists in an undisclosed iControl REST and BIG-IP TMOS Shell (tmsh) command that may allow an authenticated attacker with at least resource administrator role to execute arbitrary system commands with higher privileges.  A successful exploit can allow the attacker to cross a security boundary.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

A stored cross-site scripting (XSS) vulnerability exists in an undisclosed page of the BIG-IP Configuration utility that allows an attacker to run JavaScript in the context of the currently logged-in user.

On BIG-IP systems, undisclosed traffic can cause data corruption and unauthorized data modification in protocols which do not have message integrity protection.

When a BIG-IP Advanced WAF or ASM security policy is configured with a URL greater than 1024 characters in length for the Data Guard Protection Enforcement setting, either manually or through the automatic Policy Builder, the bd process can terminate repeatedly.

When the database variable tm.tcpudptxchecksum is configured as non-default value Software-only on a BIG-IP system, undisclosed traffic can cause the Traffic Management Microkernel (TMM) to terminate.

A validation vulnerability exists in an undisclosed URL in the Configuration utility.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Under undisclosed traffic conditions along with conditions beyond the attacker's control, hardware systems with a High-Speed Bridge (HSB) and an embedded Packet Velocity Acceleration (ePVA) chip may experience a lockup of the HSB.

When a virtual server, network address translation (NAT) object, or secure network address translation (SNAT) object uses the embedded Packet Velocity Acceleration (ePVA) feature, and the Auto Last Hop setting is disabled, undisclosed traffic can cause the Traffic Management Microkernel (TMM) to terminate. The Auto Last Hop setting is enabled globally by default. For more information about the Auto Last Hop setting, refer to K13876: Overview of the Auto Last Hop setting (15.x - 17.x). To determine which BIG-IP platforms have an ePVA chip, refer to K12837: Overview of the ePVA feature.

A vulnerability exists in the iHealth command that may allow an authenticated attacker with at least a resource administrator role to bypass tmsh restrictions and gain access to a bash shell.  For BIG-IP systems running in Appliance mode, a successful exploit can allow the attacker to cross a security boundary.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

When an iRule using an ILX::call command is configured on a virtual server, undisclosed traffic can cause the Traffic Management Microkernel (TMM) to terminate.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

When a BIG IP Advanced WAF or ASM security policy is configured on a virtual server, undisclosed requests can cause the bd process to terminate.

A vulnerability was found in the fs/inode.c:inodeinitowner() function logic of the LInux kernel that allows local users to create files with an unintended group ownership and with group execution and SGID permission bits set, in a scenario where a directory is SGID and belongs to a certain group and is writable by a user who is not a member of this group. This can lead to excessive permissions granted in case when they should not.

The Diffie-Hellman Key Agreement Protocol allows remote attackers (from the client side) to send arbitrary numbers that are actually not public keys, and trigger expensive server-side DHE modular-exponentiation calculations, aka a D(HE)at or D(HE)ater attack. The client needs very little CPU resources and network bandwidth. The attack may be more disruptive in cases where a client can require a server to select its largest supported key size. The basic attack scenario is that the client must claim that it can only communicate with DHE, and the server must be configured to allow DHE.

A vulnerability exists in an undisclosed BIG-IP Configuration utility page that may allow an attacker to spoof error messages

Impact:

An attacker may trick authenticated BIG-IP users into accessing malicious links and reflect a spoofed error message in the victim's BIG-IP Configuration utility web browser session. This is a control plane issue; there is no data plane exposure.

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

When a BIG-IP is configured with DNS caching (Such as a DNS profile with caching enabled, SSL Orchestrator, Advanced WAF DoS protection), undisclosed traffic can cause the Traffic Management Microkernel (TMM) to terminate. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

A vulnerability was found in OpenSSL 1.0.2. When an application encounters a fatal protocol error and then calls SSLshutdown() twice, OpenSSL can respond differently to the calling application if a 0 byte record is received with invalid padding compared to if a 0 byte record is received with an invalid MAC. This difference in behaviour can be detected by a remote peer, then this amounts to a padding oracle that could be used to decrypt data. In order for this to be exploitable "non-stitched" ciphersuites must be in use. Also the application must call SSLshutdown() twice even if a protocol error has occurred (applications should not do this but some do anyway). AEAD ciphersuites are not impacted. This issue does not impact OpenSSL 1.1.1 or 1.1.0.

Upstream bug: https://www.openssl.org/news/secadv/20190226.txt

Upstream Patch: https://github.com/openssl/openssl/commit/e9bbefbf0f24c57645e7ad6a5a71ae649d18ac8e

A flaw was found in the bash functionality that evaluates specially formatted environment variables passed to it from another environment. An attacker could use this feature to override or bypass restrictions to the environment to execute shell commands before restrictions have been applied. Certain services and applications allow remote unauthenticated attackers to provide environment variables, allowing them to exploit this issue.

Acknowledgements:

Red Hat would like to thank Stephane Chazelas for reporting this issue.

A flaw named SegmentSmack was found in the way the Linux kernel handled specially crafted TCP packets. A remote attacker could use this flaw to trigger time and calculation expensive calls to tcpcollapseofoqueue() and tcppruneofoqueue() functions by sending specially modified packets within ongoing TCP sessions which could lead to a CPU saturation and hence a denial of service on the system. Maintaining the denial of service condition requires continuous two-way TCP sessions to a reachable open port, thus the attacks cannot be performed using spoofed IP addresses.

A flaw was found in the Linux kernels with commit b6a2fea39318 ("mm: variable length argument support", from July 19, 2007) but without commit da029c11e6b1 ("exec:Limit arg stack to at most 75% of STKLIM", from July 7, 2017). An integer overflow in the Linux kernel's createelftables() function. A local attacker can exploit this vulnerability via a SUID-root binary and obtain full root privileges.

Referenced commits: b6a2fea39318 ("mm: variable length argument support", from July 19, 2007) https://github.com/torvalds/linux/commit/b6a2fea39318e43fee84fa7b0b90d68bed92d2ba

da029c11e6b1 ("exec: Limit arg stack to at most 75% of STKLIM", from July 7, 2017) https://github.com/torvalds/linux/commit/da029c11e6b12f321f36dac8771e833b65cec962

Additional references: https://www.qualys.com/2018/09/25/cve-2018-14634/mutagen-astronomy-integer-overflow-linux-createelftables-cve-2018-14634.txt

A use after free issue was found in the way Linux kernel's KVM hypervisor implements its device control API. While creating a device via kvmioctlcreatedevice(), device holds a reference to a VM object, latter this reference is transferred to caller's file descriptor table. If such file descriptor was to be closed, reference count to the VM object could become zero, potentially leading to use-after-free issue latter.

A user/process could use this flaw to crash the guest VM resulting in DoS issue OR potentially gain privileged access to a system.

Upstream patch: --------------- -> https://git.kernel.org/linus/cfa39381173d5f969daf43582c95ad679189cbc9

Reference: ---------- -> https://www.openwall.com/lists/oss-security/2019/02/18/2