Directory Traversal Affecting microsoft.openapi.kiota package, versions [,1.32.5)

Affected versions of this package are vulnerable to Directory Traversal through PluginsGenerationService in the plugin manifest generation code. An attacker can make the generated Copilot or Teams plugin manifest reference files outside the plugin package by supplying an OpenAPI description with an unsafe x-ai-adaptive-card or x-ai-capabilities static_template.file value, such as ../, an absolute path, or a URI. The vulnerable code copies the attacker-controlled file reference into response_semantics.static_template.file and emits it into <name>-apiplugin.json without path validation. When the manifest is later deployed, the AI host resolves the injected path, causing out-of-package file inclusion and exposing unintended local files to the plugin runtime.

Notes

• The unsafe file reference can come from either x-ai-adaptive-card or x-ai-capabilities in the source OpenAPI document, so the vulnerable input surface is broader than a single extension name.

Workarounds

• Until you can upgrade, avoid generating Copilot/Teams plugin manifests from untrusted or compromised OpenAPI descriptions, especially ones containing x-ai-adaptive-card or x-ai-capabilities static_template.file fields, to prevent path traversal or out-of-package file inclusion in the deployed plugin.

A Directory Traversal attack (also known as path traversal) aims to access files and directories that are stored outside the intended folder. By manipulating files with "dot-dot-slash (../)" sequences and its variations, or by using absolute file paths, it may be possible to access arbitrary files and directories stored on file system, including application source code, configuration, and other critical system files.

Directory Traversal vulnerabilities can be generally divided into two types:

• Information Disclosure: Allows the attacker to gain information about the folder structure or read the contents of sensitive files on the system.

st is a module for serving static files on web pages, and contains a vulnerability of this type. In our example, we will serve files from the public route.

If an attacker requests the following URL from our server, it will in turn leak the sensitive private key of the root user.

curl http://localhost:8080/public/%2e%2e/%2e%2e/%2e%2e/%2e%2e/%2e%2e/root/.ssh/id_rsa

Note %2e is the URL encoded version of . (dot).

• Writing arbitrary files: Allows the attacker to create or replace existing files. This type of vulnerability is also known as Zip-Slip.

One way to achieve this is by using a malicious zip archive that holds path traversal filenames. When each filename in the zip archive gets concatenated to the target extraction folder, without validation, the final path ends up outside of the target folder. If an executable or a configuration file is overwritten with a file containing malicious code, the problem can turn into an arbitrary code execution issue quite easily.

The following is an example of a zip archive with one benign file and one malicious file. Extracting the malicious file will result in traversing out of the target folder, ending up in /root/.ssh/ overwriting the authorized_keys file:

2018-04-15 22:04:29 .....           19           19  good.txt
2018-04-15 22:04:42 .....           20           20  ../../../../../../root/.ssh/authorized_keys

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