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This vulnerability, affecting Kiota versions prior to 1.31.1, is a code-generation literal injection issue present in multiple writer sinks. These sinks include serialization/deserialization keys, path/query parameter mappings, URL template metadata, enum/property metadata, and default value emission. The flaw occurs when malicious values from an OpenAPI description are directly emitted into the generated source code without context-appropriate escaping. An attacker can craft an OpenAPI description containing specially crafted string literals that, when processed by Kiota, break out of the intended string context. This allows the injection of additional, attacker-controlled code into the generated client. The vulnerability is only practically exploitable when the OpenAPI description used for generation is from an untrusted source or has been compromised. The following OpenAPI fragment demonstrates a malicious default value:
openapi: 3.0.1 info: Exploit Demo version: 1.0.0 components: schemas: User: type: object properties: displayName: type: string default: "\"; throw new System.Exception(\"injected\"); //"
When processed by an affected Kiota version, this payload would be emitted into the generated C code as:
public User() {
DisplayName = ""; throw new System.Exception("injected"); //";
}
This injection can occur in various locations beyond default values, including property names, path or query parameters, enum representations, and other metadata.
dailycve form:
Platform: dotnet
Version: < 1.31.1
Vulnerability : Code Generation Injection
Severity: not stated
date: not stated
Prediction: Upon 1.31.1 release
What Undercode Say:
Check your Kiota version kiota --version Upgrade to the patched version dotnet tool update --global Microsoft.OpenApi.Kiota --version 1.31.1
Code Analysis:
// Before fix (vulnerable)
public User() {
DisplayName = ""; throw new System.Exception("injected"); //";
}
// After fix (safe)
public User() {
DisplayName = "\\"; throw new System.Exception(\\"injected\\"); //";
}
Exploit:
An attacker can exploit this vulnerability by providing a malicious OpenAPI description to a developer or CI/CD pipeline that uses an affected Kiota version to generate an API client. The attacker must have the ability to influence the OpenAPI description used for generation. This could be achieved by compromising a trusted API specification repository, performing a man-in-the-middle attack during download, or tricking a developer into using a malicious OpenAPI file. When the developer generates the client, the injected code becomes part of the generated source, leading to arbitrary code execution during client initialization or when the generated code is used.
Protection from this CVE
- Upgrade Kiota: Immediately update to version 1.31.1 or later. This version includes proper escaping for all vulnerable writer sinks.
- Regenerate Clients: After upgrading, regenerate all existing API clients to replace previously generated vulnerable code with the hardened output.
- Source Trust: Only generate clients from trusted, integrity-protected OpenAPI descriptions. Verify the source of any OpenAPI file before use.
- Code Review: Perform security reviews of generated code, especially when using OpenAPI descriptions from external sources.
Impact
Successful exploitation allows an attacker to inject arbitrary code into the generated API client. This code will execute in the context of the developer’s machine during client generation and in any application that subsequently uses the generated client. The impact includes:
– Arbitrary Code Execution: Attacker-controlled code runs on the developer’s machine and within any consuming application.
– Supply Chain Compromise: Malicious code injected into a generated client can propagate to all applications that use that client.
– Data Breach: The injected code could exfiltrate sensitive data from the development environment or production applications.
– Privilege Escalation: Depending on the context, the injected code may gain elevated privileges.
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Sources:
Reported By: github.com
Extra Source Hub:
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