CVE-2022-29526: Go Incorrect Privilege Assignment Vulnerability in Versions <1.17.10 and 1.18.x <1.18.2

The Go programming language, also known as Golang, is a popular language used by developers worldwide for its simplicity, efficiency, and strong support for concurrent programming. However, even the most robust languages can contain vulnerabilities if not properly managed. In this post, we will discuss a critical vulnerability identified with the Common Vulnerabilities and Exposures (CVE) ID, CVE-2022-29526, which affects Go versions before 1.17.10 and 1.18.x before 1.18.2. This vulnerability could result in incorrect privilege assignment when the Faccessat function is called with a non-zero flags parameter, leading to incorrect access reports for a file.

Original References

1. https://github.com/golang/go/commit/fa95e9581ec843b3697ee9b6ed99f1de2556045
2. https://go-review.googlesource.com/c/go/+/383078/

Exploit Details

CVE-2022-29526 is a critical vulnerability that may result in inadvertent access to sensitive files due to the incorrect privilege assignment in Go's Faccessat function. Specifically, when the Faccessat function is called with a non-zero flags parameter, it could mistakenly report that a file is accessible even when it should not be.

The root cause of this vulnerability lies in the implementation of the Faccessat function, where improper handling of the flags parameter could lead to the incorrect reporting of file access status. In affected versions of Go, the Faccessat syscall may return  (indicating success) when it should return -1 (indicating error). The following code snippet demonstrates this issue:

package main

import (
	"fmt"
	"os"
	"syscall"
)

func main() {
	filePath := "example.txt"
	flags := uintptr(syscall.AT_EACCESS)

	if syscall.Faccessat(-1, filePath, os.R_OK, flags) !=  {
		fmt.Println("File is not accessible")
	} else {
		fmt.Println("File is accessible")
	}
}

In the above code snippet, the Faccessat function is called with the AT_EACCESS flag (which should at least restrict access to the file), but the function incorrectly returns the 'File is accessible' message, indicating a successful access test even when the file should not be accessible.

Mitigation

To mitigate this vulnerability, users running affected versions of Go (before 1.17.10 and 1.18.x before 1.18.2) should immediately update their Go installations to the patched versions 1.17.10 or later and 1.18.2 or later, respectively. The patch for this vulnerability can be found in the following change list: https://go-review.googlesource.com/c/go/+/383078/.

To update your Go installation, you can follow the official instructions provided in the Go documentation: https://golang.org/doc/install

Conclusion

In summary, CVE-2022-29526 is a critical vulnerability in Go's Faccessat function implementation, which could potentially lead to unauthorized access to sensitive files due to incorrect privilege assignment. To mitigate this vulnerability, it is crucial for users to update their Go installations to the patched versions 1.17.10 or later and 1.18.2 or later and carefully review their own code for any instances where the Faccessat function is called with a non-zero flags parameter.

Remember, staying up-to-date with software updates and security patches is an essential practice to keep your code and systems secure from potential threats.

Timeline

Published on: 06/23/2022 17:15:00 UTC
Last modified on: 08/19/2022 12:50:00 UTC