Description

This vulnerability detector identifies usage of deprecated RSA encryption functions in Go code that use the insecure PKCS#1 v1.5 padding scheme. These functions are vulnerable to padding oracle attacks and have been superseded by more secure alternatives using OAEP padding.

Detection Strategy

• Scans Go source code files that import the 'crypto/rsa' package

• Identifies function calls to deprecated RSA encryption methods: EncryptPKCS1v15, DecryptPKCS1v15, and DecryptPKCS1v15SessionKey

• Reports vulnerabilities when any of these deprecated PKCS#1 v1.5 functions are called, regardless of how the crypto/rsa package is aliased in the import statement

• Triggers on direct function calls using the RSA package alias (e.g., 'rsa.EncryptPKCS1v15()' or custom alias like 'cryptorsa.EncryptPKCS1v15()')

Vulnerable code example

package main

import (
	"crypto/rand"
	"crypto/rsa"
)

func UnsafeEncrypt(pub *rsa.PublicKey, msg []byte) ([]byte, error) {...

✅ Secure code example

package main

import (
	"crypto/rand"
	"crypto/rsa"
	"crypto/sha256"
)
...