A vulnerability in the CLI of Cisco IOS XE SD-WAN Software could allow an authenticated, local attacker to execute arbitrary commands with elevated privileges. This vulnerability is due to insufficient input validation by the system CLI. An attacker with privileges to run commands could exploit this vulnerability by first authenticating to an affected device using either local terminal access or a management shell interface and then submitting crafted input to the system CLI. A successful exploit could allow the attacker to execute commands on the underlying operating system with root-level privileges. An attacker with limited user privileges could use this vulnerability to gain complete control over the system. Note: For additional information about specific impacts, see the Details section of this advisory.
Weakness
The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as expression or command delimiters when they are sent to a downstream component.
Affected Software
| Name |
Vendor |
Start Version |
End Version |
| Ios_xe_sd-wan |
Cisco |
- (including) |
- (including) |
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