CVE-2023-24537: Go Language Source Code Parsing Infinitely Loops Caused by Large Line Numbers

It has recently come to light that there is a vulnerability within the Go programming language's parsing functions. This vulnerability, CVE-2023-24537, can cause an infinite loop when parsing Go source code containing very large line numbers. The issue arises due to an integer overflow in the parsing process, and this post delves into the details of the exploit, code snippets to showcase the issue, and original references to better understand and mitigate the problem.

Exploit Details

The vulnerability is associated with the Parse functions in Go when dealing with source code containing //line directives that feature unusually large line numbers. After a certain threshold, the line numbers result in an integer overflow, leading the parser to enter an infinite loop. This situation could potentially lead to a Denial of Service (DoS) attack, rendering the program unresponsive.

For a better understanding of this issue, consider the following code snippet, which demonstrates the vulnerability:

package main

import (
	"fmt"
	"go/parser"
	"go/token"
)

const src = `package main

//line :2147483647
func main() {
	fmt.Println("Hello, world!")
}
`

func main() {
	fset := token.NewFileSet()
	_, err := parser.ParseFile(fset, "", src, )
	if err != nil {
		fmt.Println("Error:", err)
		return
	}
	fmt.Println("Parsed successfully")
}

The Go source code supplied in src contains a //line directive, deliberately crafted with a very large line number (2147483647) that exceeds the range of int32. This leads to an integer overflow and, consequently, an infinite loop when the parser.ParseFile function is called. This results in the program becoming non-responsive, which makes it a prime target for a potential DoS attack.

Original References and Links

The vulnerability has been officially reported and documented by the Go development team. To access information about the issue, you can follow these links:

- The Go Language GitHub issue: https://github.com/golang/go/issues/41637
- The Common Vulnerabilities and Exposures (CVE) report: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-24537

Mitigation Strategies

To mitigate the potential risks associated with this vulnerability, it is vital to ensure that you use a version of the Go programming language that includes appropriate patches to handle such cases. It is recommended to keep your Go environment up-to-date using the latest official releases and security patches provided by the Go development team.

Furthermore, it is good practice to validate and sanitize input when handling source code to prevent the possibility of a maliciously crafted directive, leading to the triggering of this vulnerability.

Conclusion

By understanding the implications of the CVE-2023-24537 vulnerability and adopting mitigation strategies, you can defend your Go project against potential risks associated with large line numbers causing infinite loops in Go's parsing functions. Whether you are a developer or an organization, make sure to follow best practices and stay apprised of updates and patches to ensure your systems remain secure.

Timeline

Published on: 04/06/2023 16:15:00 UTC
Last modified on: 04/13/2023 19:09:00 UTC