Moby up to 20.10.18 failing open

Summaryinfo

A vulnerability was found in Moby and classified as problematic. The affected element is an unknown function. Executing a manipulation can lead to failing open. This vulnerability is handled as CVE-2023-28840. The attack can be executed remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in Moby. This vulnerability affects an unknown code. The manipulation with an unknown input leads to a failing open vulnerability. The CWE definition for the vulnerability is CWE-636. When the product encounters an error condition or failure, its design requires it to fall back to a state that is less secure than other options that are available, such as selecting the weakest encryption algorithm or using the most permissive access control restrictions. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

Moby is an open source container framework developed by Docker Inc. that is distributed as Docker, Mirantis Container Runtime, and various other downstream projects/products. The Moby daemon component (`dockerd`), which is developed as moby/moby, is commonly referred to as *Docker*. Swarm Mode, which is compiled in and delivered by default in dockerd and is thus present in most major Moby downstreams, is a simple, built-in container orchestrator that is implemented through a combination of SwarmKit and supporting network code. The overlay network driver is a core feature of Swarm Mode, providing isolated virtual LANs that allow communication between containers and services across the cluster. This driver is an implementation/user of VXLAN, which encapsulates link-layer (Ethernet) frames in UDP datagrams that tag the frame with a VXLAN Network ID (VNI) that identifies the originating overlay network. In addition, the overlay network driver supports an optional, off-by-default encrypted mode, which is especially useful when VXLAN packets traverses an untrusted network between nodes. Encrypted overlay networks function by encapsulating the VXLAN datagrams through the use of the IPsec Encapsulating Security Payload protocol in Transport mode. By deploying IPSec encapsulation, encrypted overlay networks gain the additional properties of source authentication through cryptographic proof, data integrity through check-summing, and confidentiality through encryption. When setting an endpoint up on an encrypted overlay network, Moby installs three iptables (Linux kernel firewall) rules that enforce both incoming and outgoing IPSec. These rules rely on the u32 iptables extension provided by the xt_u32 kernel module to directly filter on a VXLAN packet's VNI field, so that IPSec guarantees can be enforced on encrypted overlay networks without interfering with other overlay networks or other users of VXLAN. Two iptables rules serve to filter incoming VXLAN datagrams with a VNI that corresponds to an encrypted network and discards unencrypted datagrams. The rules are appended to the end of the INPUT filter chain, following any rules that have been previously set by the system administrator. Administrator-set rules take precedence over the rules Moby sets to discard unencrypted VXLAN datagrams, which can potentially admit unencrypted datagrams that should have been discarded. The injection of arbitrary Ethernet frames can enable a Denial of Service attack. A sophisticated attacker may be able to establish a UDP or TCP connection by way of the container’s outbound gateway that would otherwise be blocked by a stateful firewall, or carry out other escalations beyond simple injection by smuggling packets into the overlay network. Patches are available in Moby releases 23.0.3 and 20.10.24. As Mirantis Container Runtime's 20.10 releases are numbered differently, users of that platform should update to 20.10.16. Some workarounds are available. Close the VXLAN port (by default, UDP port 4789) to incoming traffic at the Internet boundary to prevent all VXLAN packet injection, and/or ensure that the `xt_u32` kernel module is available on all nodes of the Swarm cluster.

The weakness was released 04/05/2023. The advisory is shared for download at github.com. This vulnerability was named CVE-2023-28840 since 03/24/2023. There are neither technical details nor an exploit publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 235068 (Ubuntu 18.04 LTS : Docker vulnerabilities (USN-7474-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 23.0.3 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (235068) and CERT Bund (WID-SEC-2023-1183). Once again VulDB remains the best source for vulnerability data.

Affected

• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• Gentoo Linux
• Red Hat OpenShift
• Open Source docker
• SUSE openSUSE
• RESF Rocky Linux

Productinfo

Name

• Moby

Version

• 1.11
• 17.06.0
• 20.10.9
• 20.10.14
• 20.10.18

Website

• Product: https://github.com/moby/moby/

CPE 2.3info

• 🔍
• 🔍
• 🔍

CPE 2.2info

• 🔍
• 🔍
• 🔍

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Once again VulDB remains the best source for vulnerability data.

Discussion