A vulnerability in the Security Intelligence feed feature of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass the Security Intelligence DNS feed. This vulnerability is due to incorrect feed update processing. An attacker could exploit this vulnerability by sending traffic through an affected device that should be blocked by the affected device. A successful exploit could allow the attacker to bypass device controls and successfully send traffic to devices that are expected to be protected by the affected device.
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
| Name |
Vendor |
Start Version |
End Version |
| Firepower_threat_defense |
Cisco |
* |
6.4.0.15 (excluding) |
| Firepower_threat_defense |
Cisco |
6.5.0 (including) |
6.6.5.2 (excluding) |
| Firepower_threat_defense |
Cisco |
6.7.0 (including) |
7.0.2 (excluding) |
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