A vulnerability in the CLI of Cisco IOS XE Software could allow an authenticated, local attacker with administrative privileges to execute arbitrary commands as root on the underlying operating system of an affected device.
This vulnerability is due to insufficient validation of user arguments that are passed to specific CLI commands. An attacker could exploit this vulnerability by logging in to the device CLI with valid administrative (level 15) credentials and using crafted commands at the CLI prompt. A successful exploit could allow the attacker to execute arbitrary commands as root.
Weakness
The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as parameter or argument delimiters when they are sent to a downstream component.
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