simple-git, an interface for running git commands in any node.js application, enables applications to execute Git operations from JavaScript. Prior to 4.0.0, the default blockUnsafeOperationsPlugin compares parsed option names with literal dangerous option spellings while Git accepts unambiguous long-option abbreviations. Attacker-influenced push arguments such as abbreviated –receive-pack or –exec forms can therefore bypass detectVulnerableFlags, reach git push against a local or file remote or an attacker-influenced receive-pack target, and cause Git to invoke an attacker-selected command in consumers that expose those arguments. The clone-side abbreviation handling does not protect the push path. This issue is fixed in 4.0.0.
Weakness
The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component.
Extended Description
Many protocols and products have their own custom command language. While OS or shell command strings are frequently discovered and targeted, developers may not realize that these other command languages might also be vulnerable to attacks.
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.
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/136.html
- https://cwe.mitre.org/data/definitions/15.html
- https://cwe.mitre.org/data/definitions/183.html
- https://cwe.mitre.org/data/definitions/248.html
- https://cwe.mitre.org/data/definitions/40.html
- https://cwe.mitre.org/data/definitions/43.html
- https://cwe.mitre.org/data/definitions/75.html
- https://cwe.mitre.org/data/definitions/76.html