CWE Rule 693

Protection Mechanism Failure

Since R2024a

Description

The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.

Polyspace Implementation

The rule checker checks for Nonsecure SSL/TLS protocol.

Examples

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Nonsecure SSL/TLS protocol

Issue

This issue occurs when you do not disable nonsecure protocols in an SSL_CTX or SSL context object before using the object for handling SSL/TLS connections.

For instance, you disable the protocols SSL2.0 and TLS1.0 but forget to disable the protocol SSL3.0, which is also considered weak.

/* Create and configure context */
ctx = SSL_CTX_new(SSLv23_method());
SSL_CTX_set_options(ctx, SSL_OP_NO_SSLv2|SSL_OP_NO_TLSv1);

/* Use context to handle connection */
ssl = SSL_new(ctx);
SSL_set_fd(ssl, NULL);
ret = SSL_connect(ssl);

Risk

The protocols SSL2.0, SSL3.0, and TLS1.0 are considered weak in the cryptographic community. Using one of these protocols can expose your connections to cross-protocol attacks. The attacker can decrypt an RSA ciphertext without knowing the RSA private key.

Fix

Disable the nonsecure protocols in the context object before using the object to handle connections.

/* Create and configure context */
ctx = SSL_CTX_new(SSLv23_method());
SSL_CTX_set_options(ctx, SSL_OP_NO_SSLv2|SSL_OP_NO_SSLv3|SSL_OP_NO_TLSv1);

Example — Nonsecure Protocols Not Disabled


#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <openssl/ssl.h>
#include <openssl/err.h>


#define fatal_error() exit(-1)

int ret;
int func(){
  SSL_CTX *ctx;
  SSL *ssl;

  SSL_library_init();

  /* context configuration */
  ctx = SSL_CTX_new(SSLv23_client_method()); 
  if (ctx==NULL) fatal_error();

  ret = SSL_CTX_use_certificate_file(ctx, "cert.pem", SSL_FILETYPE_PEM); 
  if (ret <= 0) fatal_error();

  ret = SSL_CTX_load_verify_locations(ctx, NULL, "ca/path"); 
  if (ret <= 0) fatal_error();

  /* Handle connection */
  ssl = SSL_new(ctx);
  if (ssl==NULL) fatal_error();
  SSL_set_fd(ssl, NULL);

  return SSL_connect(ssl);  //Noncompliant
}

In this example, the protocols SSL2.0, SSL3.0, and TLS1.0 are not disabled in the context object before the object is used for a new connection.

Correction — Disable Nonsecure Protocols

Disable nonsecure protocols before using the objects for a new connection. Use the function SSL_CTX_set_options to disable the protocols SSL2.0, SSL3.0, and TLS1.0.


#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <openssl/ssl.h>
#include <openssl/err.h>


#define fatal_error() exit(-1)

int ret;
int func(){
  SSL_CTX *ctx;
  SSL *ssl;

  SSL_library_init();

  /* context configuration */
  ctx = SSL_CTX_new(SSLv23_client_method()); 
  if (ctx==NULL) fatal_error();

  SSL_CTX_set_options(ctx, SSL_OP_NO_SSLv2|SSL_OP_NO_SSLv3|SSL_OP_NO_TLSv1);

  ret = SSL_CTX_use_certificate_file(ctx, "cert.pem", SSL_FILETYPE_PEM); 
  if (ret <= 0) fatal_error();

  ret = SSL_CTX_load_verify_locations(ctx, NULL, "ca/path"); 
  if (ret <= 0) fatal_error();

  /* Handle connection */
  ssl = SSL_new(ctx);
  if (ssl==NULL) fatal_error();
  SSL_set_fd(ssl, NULL);

  return SSL_connect(ssl); 
}

Check Information

Category: Others

PQL Name: std.cwe_native.R693

Version History

Introduced in R2024a