CVE-2023-29404 - An in-depth look at the "go command" vulnerability that enables arbitrary code execution at build time when using cgo

As developers, security should always be at the forefront of our minds--especially when working with open-source languages and libraries. Today, we'll be discussing the recent vulnerability discovered in the popular Go (Golang) programming language, specifically in the go command. This vulnerability, assigned the code CVE-2023-29404, allows for arbitrary code execution at build time when using cgo. This means that when a developer runs a go get on a malicious module, or when executing other commands that build untrusted code, they may open themselves up to potential risks.

In this post, we'll discuss the details of the exploit, explore a code snippet demonstrating its use, and provide links to the original references. It's crucial to understand this vulnerability, as it affects the usage of both the gc and gccgo compilers.

Exploit Details

The CVE-2023-29404 vulnerability lies within the linker flags, which are specified via the #cgo LDFLAGS directive. The arguments for several flags are considered optional when they should be non-optional. The vulnerability comes into play when these non-optional flags are incorrectly considered optional, allowing disallowed flags to be smuggled through the LDFLAGS sanitization.

The following snippet showcases the vulnerability with a malicious cgo package

package badpackage

// #cgo LDFLAGS: -inputpath=$
// #include <stdio.h>
import "C"

func MaliciousFunction() {
  C.puts(C.CString("This is a malicious function executing arbitrary code"))
}

When the Go command processes this malicious package, it mistakenly considers the -inputpath=$ flag as optional, which allows the attacker to bypass the sanitization of the LDFLAGS. Consequently, the input path will grant the attacker the ability to execute arbitrary code.

Original References

For those who want to dive deeper into the CVE-2023-29404 vulnerability, here are some essential links and resources:

1. Official CVE - CVE-2023-29404: The original description of the vulnerability.
2. Go Issue 49984: The GitHub issue where the vulnerability was initially reported and discussed by the Go community.
3. Go Security Documentation: Official documentation on Go language security, including general guidance for keeping your projects secure.

Takeaways and Mitigation Measures

As developers, it's increasingly important to remain vigilant and proactive about security issues--particularly when working with open-source languages like Go, which are widely adopted across the development community. Staying informed about crucial vulnerabilities like CVE-2023-29404 should be part of your professional responsibility.

To mitigate the risk of arbitrary code execution through your go command, please ensure you are using the latest version of the Go programming language and consult the official documentation to adhere to best security practices. Additionally, always verify the authenticity and intent of third-party libraries and packages before incorporating them into your projects. Finally, consider discussing security issues and following updates on community forums like GitHub to stay up-to-date on the latest information regarding potential vulnerabilities.

Timeline

Published on: 06/08/2023 21:15:00 UTC
Last modified on: 06/16/2023 12:54:00 UTC