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Insecure encryption algorithm - SHA1

Need​

Upgrade to a secure encryption algorithm

Context​

  • Usage of Go 1.16 for developing efficient and scalable applications
  • Usage of gin-gonic/gin for building web applications in Go

Description​

Non compliant code​

package main

import (
	"crypto/sha1"
	"fmt"
	"github.com/gin-gonic/gin"
	"io"
)

func main() {
	r := gin.Default()

	r.GET("/hash/:input", func(c *gin.Context) {
		input := c.Param("input")
		h := sha1.New()
		io.WriteString(h, input)
		sha1Hash := fmt.Sprintf("%x", h.Sum(nil))

		c.JSON(200, gin.H{
			"hash": sha1Hash,
		})
	})

	r.Run()
}

In the above code, we have a simple Go server using the Gin framework. It exposes an endpoint /hash/:input, which takes an input string as a parameter, hashes it using the SHA1 algorithm, and returns the hash as a JSON response.

The vulnerability lies in the use of the SHA1 hashing algorithm. SHA1 is considered insecure due to known vulnerabilities, including collision attacks, where two different inputs can produce the same hash. This can lead to potential security issues such as data integrity violations and unauthorized access.

The crypto/sha1 library in Go is used to create a new hash, and the io.WriteString function is used to write the input string to the hash. The h.Sum(nil) function is then used to calculate the final hash.

The problem is in this line: h := sha1.New(). Here, a new SHA1 hash is being created, which is the root of the vulnerability. The server is using this insecure SHA1 hash to process sensitive data, which could lead to various security issues if an attacker were able to exploit the known vulnerabilities in SHA1.

Steps​

  • Replace the SHA1 algorithm with a more secure hashing algorithm, such as SHA256 or bcrypt.
  • Update the import statement to import the correct cryptographic library for the chosen algorithm.
  • Modify the code to use the new hashing algorithm instead of SHA1.
  • Ensure that the chosen algorithm is considered secure and not vulnerable to known attacks.
  • Test the updated code thoroughly to ensure it functions correctly and securely.

Compliant code​

package main

import (
	"crypto/sha256"
	"fmt"
	"github.com/gin-gonic/gin"
	"io"
)

func main() {
	r := gin.Default()

	r.GET("/hash/:input", func(c *gin.Context) {
		input := c.Param("input")
		h := sha256.New()
		io.WriteString(h, input)
		sha256Hash := fmt.Sprintf("%x", h.Sum(nil))

		c.JSON(200, gin.H{
			"hash": sha256Hash,
		})
	})

	r.Run()
}

The original code was using the SHA1 hashing algorithm, which is considered insecure due to its vulnerability to collision attacks. In the updated code, we have replaced SHA1 with SHA256, which is a much more secure hashing algorithm.

The changes made are as follows:

  1. The import statement has been updated to import the crypto/sha256 package instead of crypto/sha1.

  2. The sha1.New() function call has been replaced with sha256.New(). This creates a new hash.Hash computing the SHA256 checksum.

  3. The variable sha1Hash has been renamed to sha256Hash to reflect the change in the hashing algorithm.

  4. The resulting SHA256 hash is then returned in the JSON response.

This updated code should now be resistant to the known vulnerabilities of SHA1. However, it is recommended to thoroughly test the updated code to ensure it functions correctly and securely.

References​

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