CVE-2024-39515

An Improper Validation of Consistency within Input vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an unauthenticated network-based attacker sending a specifically malformed BGP packet to cause rpd to crash and restart, resulting in a Denial of Service (DoS). Continued receipt and processing of this packet will create a sustained Denial of Service (DoS) condition.

In some cases, rpd fails to restart requiring a manual restart via the restart routing CLI command.

This issue only affects systems with BGP traceoptions enabled and

requires a BGP session to be already established. Systems without BGP traceoptions enabled are not affected by this issue.

This issue affects iBGP and eBGP, and both IPv4 and IPv6 are affected by this vulnerability.

This issue affects:

Junos OS: 

• All versions before 21.4R3-S8, 
• 22.2 before 22.2R3-S5, 
• 22.3 before 22.3R3-S4, 
• 22.4 before 22.4R3-S3, 
• 23.2 before 23.2R2-S2, 
• 23.4 before 23.4R2; 

Junos OS Evolved: 

• All versions before 21.4R3-S8-EVO, 
• 22.2-EVO before 22.2R3-S5-EVO, 
• 22.3-EVO before 22.3R3-S4-EVO, 
• 22.4-EVO before 22.4R3-S3-EVO, 
• 23.2-EVO before 23.2R2-S2-EVO, 
• 23.4-EVO before 23.4R2-EVO.

Weakness

The product receives a complex input with multiple elements or fields that must be consistent with each other, but it does not validate or incorrectly validates that the input is actually consistent.

Affected Software

Extended Description

Some input data can be structured with multiple elements or fields that must be consistent with each other, e.g. a number-of-items field that is followed by the expected number of elements. When such complex inputs are inconsistent, attackers could trigger unexpected errors, cause incorrect actions to take place, or exploit latent vulnerabilities.

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.

References

• https://supportportal.juniper.net/JSA88099
• https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/statement/traceoptions-edit-protocols-bgp.html