corydolphin/flask-cors is vulnerable to log injection when the log level is set to debug. An attacker can inject fake log entries into the log file by sending a specially crafted GET request containing a CRLF sequence in the request path. This vulnerability allows attackers to corrupt log files, potentially covering tracks of other attacks, confusing log post-processing tools, and forging log entries. The issue is due to improper output neutralization for logs.
Weakness
The product does not neutralize or incorrectly neutralizes output that is written to logs.
Extended Description
This can allow an attacker to forge log entries or inject malicious content into logs.
Log forging vulnerabilities occur when:
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