CVE-2022-22219

Due to the Improper Handling of an Unexpected Data Type in the processing of EVPN routes on Juniper Networks Junos OS and Junos OS Evolved, an attacker in direct control of a BGP client connected to a route reflector, or via a machine in the middle (MITM) attack, can send a specific EVPN route contained within a BGP Update, triggering a routing protocol daemon (RPD) crash, leading to a Denial of Service (DoS) condition. Continued receipt and processing of these specific EVPN routes could create a sustained Denial of Service (DoS) condition. This issue only occurs on BGP route reflectors, only within a BGP EVPN multicast environment, and only when one or more BGP clients have leave-sync-route-oldstyle enabled. This issue affects: Juniper Networks Junos OS 21.3 versions prior to 21.3R3-S2; 21.4 versions prior to 21.4R2-S2, 21.4R3; 22.1 versions prior to 22.1R1-S2, 22.1R3; 22.2 versions prior to 22.2R2. Juniper Networks Junos OS Evolved 21.3 version 21.3R1-EVO and later versions prior to 21.4R3-EVO; 22.1 versions prior to 22.1R1-S2-EVO, 22.1R3-EVO; 22.2 versions prior to 22.2R2-EVO. This issue does not affect: Juniper Networks Junos OS versions prior to 21.3R1. Juniper Networks Junos OS Evolved versions prior to 21.3R1-EVO.

Weakness

The product does not handle or incorrectly handles when a particular element is not the expected type, e.g. it expects a digit (0-9) but is provided with a letter (A-Z).

Affected Software

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/48.html

References

• https://kb.juniper.net/JSA69898
• https://www.juniper.net/documentation/us/en/software/junos/evpn-vxlan/topics/ref/statement/evpn-edit-routing-instances-protocols.html
• https://kb.juniper.net/JSA69898
• https://www.juniper.net/documentation/us/en/software/junos/evpn-vxlan/topics/ref/statement/evpn-edit-routing-instances-protocols.html