Inspektor Gadget is a set of tools and framework for data collection and system inspection on Kubernetes clusters and Linux hosts using eBPF. The ig binary provides a subcommand for image building, used to generate custom gadget OCI images. A part of this functionality is implemented in the file inspektor-gadget/cmd/common/image/build.go. The Makefile.build file is the Makefile template employed during the building process. This file includes user-controlled data in an unsafe fashion, specifically some parameters are embedded without an adequate escaping in the commands inside the Makefile. Prior to version 0.48.1, this implementation is vulnerable to command injection: an attacker able to control values in the buildOptions structure would be able to execute arbitrary commands during the building process. An attacker able to exploit this vulnerability would be able to execute arbitrary command on the Linux host where the ig command is launched, if images are built with the --local flag or on the build container invoked by ig, if the --local flag is not provided. The buildOptions structure is extracted from the YAML gadget manifest passed to the ig image build command. Therefore, the attacker would need a way to control either the full build.yml file passed to the ig image build command, or one of its options. Typically, this could happen in a CI/CD scenario that builds untrusted gadgets to verify correctness. Version 0.48.1 fixes the issue.
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