An Improper Handling of Missing Special Element vulnerability in the SSL plugin of Juniper Networks Junos OS on SRX Series allows a network-based, unauthenticated attacker to cause a Denial-of-Service (DoS).
This issue is will occur when ssl-proxy is configured on SRX platforms and during a TLS session-resumption attempt a specifically malformed TLS message is received. This results in an invalid pointer access and PFE crash which causes a temporary loss of traffic forwarding until the PFE automatically recovers. The exact internal timing to trigger this issue is outside the attackers direct control.This issue affects Junos OS on SRX Series:
- All versions before 23.2R2-S5;
- 23.4 versions before 23.4R2-S5;
- 24.2 versions before 24.2R2-S2;
- 24.4 versions before 24.4R2.
Weakness
The product receives input from an upstream component, but it does not handle or incorrectly handles when an expected special element is missing.
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.