Limit the execution time of RSA public key check

Fixes CVE-2023-6237 If a large and incorrect RSA public key is checked with EVP_PKEY_public_check() the computation could take very long time due to no limit being applied to the RSA public key size and unnecessarily high number of Miller-Rabin algorithm rounds used for non-primality check of the modulus. Now the keys larger than 16384 bits (OPENSSL_RSA_MAX_MODULUS_BITS) will fail the check with RSA_R_MODULUS_TOO_LARGE error reason. Also the number of Miller-Rabin rounds was set to 5. Reviewed-by: Neil Horman <nhorman@openssl.org> Reviewed-by: Matt Caswell <matt@openssl.org> (Merged from #23243) (cherry picked from commit e09fc1d)
openssl · Jan 15, 2024 · 0b0f7ab · 0b0f7ab
1 parent 9aee66b
commit 0b0f7ab
Show file tree

Hide file tree

Showing 3 changed files with 56 additions and 2 deletions.
diff --git a/crypto/rsa/rsa_sp800_56b_check.c b/crypto/rsa/rsa_sp800_56b_check.c
@@ -289,6 +289,11 @@ int ossl_rsa_sp800_56b_check_public(const RSA *rsa)
         return 0;
 
     nbits = BN_num_bits(rsa->n);
+    if (nbits > OPENSSL_RSA_MAX_MODULUS_BITS) {
+        ERR_raise(ERR_LIB_RSA, RSA_R_MODULUS_TOO_LARGE);
+        return 0;
+    }
+
 #ifdef FIPS_MODULE
     /*
      * (Step a): modulus must be 2048 or 3072 (caveat from SP800-56Br1)
@@ -324,7 +329,8 @@ int ossl_rsa_sp800_56b_check_public(const RSA *rsa)
         goto err;
     }
 
-    ret = ossl_bn_miller_rabin_is_prime(rsa->n, 0, ctx, NULL, 1, &status);
+    /* Highest number of MR rounds from FIPS 186-5 Section B.3 Table B.1 */
+    ret = ossl_bn_miller_rabin_is_prime(rsa->n, 5, ctx, NULL, 1, &status);
 #ifdef FIPS_MODULE
     if (ret != 1 || status != BN_PRIMETEST_COMPOSITE_NOT_POWER_OF_PRIME) {
 #else

diff --git a/test/recipes/91-test_pkey_check.t b/test/recipes/91-test_pkey_check.t
@@ -70,7 +70,7 @@ push(@positive_tests, (
     "dhpkey.pem"
     )) unless disabled("dh");
 
-my @negative_pubtests = ();
+my @negative_pubtests = ("rsapub_17k.pem");  # Too big RSA public key
 
 push(@negative_pubtests, (
     "dsapub_noparam.der"

diff --git a/test/recipes/91-test_pkey_check_data/rsapub_17k.pem b/test/recipes/91-test_pkey_check_data/rsapub_17k.pem
@@ -0,0 +1,48 @@
+-----BEGIN PUBLIC KEY-----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+-----END PUBLIC KEY-----