Add: smb_cmac_aes_signature, smb_gmac_aes_signature

For an easier handling of smb packets new functions the functions: - smb_cmac_aes_signature, - smb_gmac_aes_signature got introduced for aes cmac and gmac handling. To use the functions you need a 64 byte long buffer and a key (with either 16 bytes for AES-129, 24 bytes for AES-192 or 32 bytes for AES-256) both functions will return the packet including the first 16 bytes of the signature (therefore AES-128 should be prefered). As an example you can create a `smb-packet-sign.nasl`: ``` key = "764efa883dda1e11"; neg_prot = raw_string( 0xfe, 0x53, 0x4d, 0x42 ); # Protocol Identifier neg_prot += raw_string( 0x40, 0x00 ); # Structure Size neg_prot += raw_string( 0x01, 0x00 ); # CreditCharge neg_prot += raw_string( 0x00, 0x00, 0x00, 0x00 ); # Status neg_prot += raw_string( 0x00, 0x00 ); # Negotiate Protocol Command neg_prot += raw_string( 0x00, 0x00 ); # Credit Request neg_prot += raw_string( 0x00, 0x00, 0x00, 0x00 ); # Flags neg_prot += raw_string( 0x00, 0x00, 0x00, 0x00 ); # Next Command --> Compound Request neg_prot += raw_string( 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ); # Message ID neg_prot += raw_string( 0x00, 0x00, 0x00, 0x00 ); # Reserved neg_prot += raw_string( 0x00, 0x00, 0x00, 0x00 ); # TreeID neg_prot += raw_string( 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x42, 0x42 ); # SessionID neg_prot += raw_string( 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ); # Signature neg_prot += raw_string( 0x42, 0x42 ); # Structure Size neg_prot += raw_string( 0x04, 0x00 ); # Dialect Count neg_prot += raw_string( 0x01, 0x00 ); # Security Mode neg_prot += raw_string( 0x00, 0x00 ); # Reserved neg_prot += raw_string( 0x00, 0x00, 0x00, 0x00 ); # Capabilities TBD add Encyrption neg_prot += raw_string( 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ); # Client GUID neg_prot += raw_string( 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ); # Different depending on dialect neg_prot += raw_string( 0x02, 0x02 ); # SMB 2.0.2 neg_prot += raw_string( 0x10, 0x02 ); # SMB 2.1 neg_prot += raw_string( 0x00, 0x03 ); # SMB 3.0 neg_prot += raw_string( 0x02, 0x03 ); # SMB 3.0.2 display("Original:"); display(hexstr(neg_prot)); display("SHA256 (cut to 16):"); sha256sig = get_smb2_signature( buf:neg_prot, key:key ); display(hexstr(sha256sig)); display("smb_cmac_aes_signature (128 => 16 keylen):"); cmac_aes = smb_cmac_aes_signature( buf:neg_prot, key:key ); display(hexstr(cmac_aes)); display("smb_gmac_aes_signature (128 => 16 keylen):"); gmac_aes = smb_cmac_aes_signature( buf:neg_prot, key:key ); display(hexstr(gmac_aes)); ``` The corresponding hash will be between `4242`.
greenbone · May 13, 2022 · 45d777c · 45d777c
1 parent 375969a
commit 45d777c
Show file tree

Hide file tree

Showing 8 changed files with 280 additions and 156 deletions.
diff --git a/.gitignore b/.gitignore
@@ -2,3 +2,4 @@ build/
 nasl/nasl_grammar.output
 nasl/nasl_grammar.tab.c
 nasl/nasl_grammar.tab.h
+.cache/
diff --git a/nasl/CMakeLists.txt b/nasl/CMakeLists.txt
@@ -165,7 +165,7 @@ endif (NOT BISON_FOUND)
 set (FILES arc4.c capture_packet.c charcnv.c exec.c genrand.c hmacmd5.c
      iconv.c lint.c md4.c md5.c nasl.c nasl_builtin_find_service.c
      nasl_builtin_openvas_tcp_scanner.c nasl_builtin_synscan.c
-     nasl_cmd_exec.c nasl_crypto2.c nasl_frame_forgery.c nasl_snmp.c nasl_ssh.c
+     nasl_cmd_exec.c nasl_crypt_helper.c nasl_crypto2.c nasl_frame_forgery.c nasl_snmp.c nasl_ssh.c
      nasl_cert.c nasl_crypto.c nasl_debug.c nasl_func.c nasl_grammar.tab.c nasl_host.c
      nasl_http.c nasl_init.c nasl_lex_ctxt.c nasl_misc_funcs.c nasl_scanner_glue.c
      nasl_packet_forgery.c nasl_packet_forgery_v6.c nasl_signature.c nasl_smb.c

diff --git a/nasl/nasl_crypt_helper.c b/nasl/nasl_crypt_helper.c
@@ -0,0 +1,198 @@
+#include "../misc//support.h"
+#include "nasl_crypto_helper.h"
+#include "nasl_debug.h"
+
+#include <assert.h>
+#include <ctype.h>
+#include <gcrypt.h>
+#include <glib.h>
+#include <gpg-error.h>
+#include <gvm/base/logging.h>
+#include <stddef.h>
+#include <stdlib.h>
+
+void *
+hmac_md5_for_prf (const void *key, int keylen, const void *buf, int buflen)
+{
+  void *signature = g_malloc0 (16);
+  gsize signlen = 16;
+  GHmac *hmac;
+
+  hmac = g_hmac_new (G_CHECKSUM_MD5, key, keylen);
+  g_hmac_update (hmac, buf, buflen);
+  g_hmac_get_digest (hmac, signature, &signlen);
+  g_hmac_unref (hmac);
+  return signature;
+}
+
+void *
+hmac_sha1 (const void *key, int keylen, const void *buf, int buflen)
+{
+  void *signature = g_malloc0 (20);
+  gsize signlen = 20;
+  GHmac *hmac;
+
+  hmac = g_hmac_new (G_CHECKSUM_SHA1, key, keylen);
+  g_hmac_update (hmac, buf, buflen);
+  g_hmac_get_digest (hmac, signature, &signlen);
+  g_hmac_unref (hmac);
+  return signature;
+}
+
+void *
+hmac_sha256 (const void *key, int keylen, const void *buf, int buflen)
+{
+  void *signature = g_malloc0 (32);
+  gsize signlen = 32;
+  GHmac *hmac;
+
+  hmac = g_hmac_new (G_CHECKSUM_SHA256, key, keylen);
+  g_hmac_update (hmac, buf, buflen);
+  g_hmac_get_digest (hmac, signature, &signlen);
+  g_hmac_unref (hmac);
+  return signature;
+}
+
+void *
+hmac_sha384 (const void *key, int keylen, const void *buf, int buflen)
+{
+  gcry_md_hd_t hd;
+  gcry_error_t err;
+  void *ret;
+
+  if (!buf || buflen <= 0)
+    return NULL;
+
+  err = gcry_md_open (&hd, GCRY_MD_SHA384, key ? GCRY_MD_FLAG_HMAC : 0);
+  if (err)
+    {
+      g_message ("nasl_gcrypt_hash(): gcry_md_open failed: %s/%s",
+                 gcry_strsource (err), gcry_strerror (err));
+      return NULL;
+    }
+
+  if (key)
+    {
+      err = gcry_md_setkey (hd, key, keylen);
+      if (err)
+        {
+          g_message ("nasl_gcrypt_hash(): gcry_md_setkey failed: %s/%s",
+                     gcry_strsource (err), gcry_strerror (err));
+          return NULL;
+        }
+    }
+
+  gcry_md_write (hd, buf, buflen);
+  ret = g_memdup2 (gcry_md_read (hd, 0), 48);
+  gcry_md_close (hd);
+  return ret;
+}
+
+gpg_err_code_t
+mac (const char *key, const size_t key_len, const char *data,
+     const size_t data_len, const char *iv, const size_t iv_len, int algo,
+     int flags, char **out, size_t *out_len)
+{
+  // guardian
+  gpg_err_code_t result = 0;
+  gcry_mac_hd_t hd;
+  if (key == NULL || key_len < 1)
+    return GPG_ERR_MISSING_KEY;
+  if (data == NULL || data_len < 1)
+    return GPG_ERR_MISSING_VALUE;
+  if (out == NULL)
+    {
+      return GPG_ERR_GENERAL;
+    }
+  if ((result = gcry_mac_open (&hd, algo, flags, NULL)))
+    return result;
+  if ((result = gcry_mac_setkey (hd, key, key_len)))
+    goto cexit;
+  if (iv && (result = gcry_mac_setiv (hd, iv, iv_len)))
+    goto cexit;
+  if ((result = gcry_mac_write (hd, data, data_len)))
+    goto cexit;
+
+  *out_len = gcry_mac_get_algo_maclen (algo);
+  if ((*out = calloc (*out_len, sizeof (*out))) == NULL)
+    {
+      result = GPG_ERR_ENOMEM;
+      goto cexit;
+    }
+  if ((result = gcry_mac_read (hd, *out, out_len)))
+    goto cexit;
+
+cexit:
+  gcry_mac_close (hd);
+  return result;
+}
+
+static gcry_error_t
+smb_sign (const int algo, const char *key, const size_t key_len, char *buf,
+          const size_t buf_len, char **out)
+{
+  gcry_error_t error = GPG_ERR_NO_ERROR;
+  char *signature = NULL;
+  size_t signature_len;
+  if (buf == NULL || buf_len < 64)
+    {
+      return GPG_ERR_NO_VALUE;
+    }
+  if (key == NULL || key_len < 16)
+    return GPG_ERR_NO_KEY;
+  memset ((char *) buf + 48, 0, 16);
+  switch (algo)
+    {
+    case GCRY_MAC_GMAC_AES:
+    case GCRY_MAC_CMAC_AES:
+      if ((error = mac (key, key_len, buf, buf_len, NULL, 0, algo,
+                        GCRY_MAC_FLAG_SECURE, &signature, &signature_len)))
+        goto exit;
+      break;
+    case G_CHECKSUM_SHA256:
+      signature = hmac_sha256 (key, key_len, buf, buf_len);
+      break;
+    default:
+      // not defined;
+      error = GPG_ERR_UNKNOWN_ALGORITHM;
+      goto exit;
+    }
+  // TODO is 16 hard coded or should it be signature_len?
+  *out = g_malloc0 (buf_len);
+  memcpy (*out, buf, buf_len);
+  memcpy (*out + 48, signature, 16);
+  free (signature);
+exit:
+  return error;
+}
+
+tree_cell *
+nasl_smb_sign (const int algo, lex_ctxt *lexic)
+{
+  char *key, *buf, *res;
+  int keylen, buflen;
+  gcry_error_t error;
+  tree_cell *retc = NULL;
+
+  key = get_str_var_by_name (lexic, "key");
+  buf = get_str_var_by_name (lexic, "buf");
+  keylen = get_var_size_by_name (lexic, "key");
+  buflen = get_var_size_by_name (lexic, "buf");
+
+  switch ((error = smb_sign (algo, key, keylen, buf, buflen, &res)))
+    {
+    case GPG_ERR_NO_ERROR:
+      retc = alloc_typed_cell (CONST_DATA);
+      retc->x.str_val = res;
+      retc->size = buflen;
+      break;
+    case GPG_ERR_MISSING_KEY:
+    case GPG_ERR_MISSING_VALUE:
+      nasl_perror (lexic, "Syntax: nasl_mac: Missing key, or data argument");
+      break;
+    default:
+      nasl_perror (lexic, "Internal: %s.", gcry_strerror (error));
+    }
+
+  return retc;
+}
diff --git a/nasl/nasl_crypto.c b/nasl/nasl_crypto.c
@@ -28,6 +28,7 @@
 #include "../misc/support.h"
 #include "exec.h"
 #include "hmacmd5.h"
+#include "nasl_crypto_helper.h"
 #include "nasl_debug.h"
 #include "nasl_func.h"
 #include "nasl_global_ctxt.h"
@@ -44,6 +45,7 @@
 #include <gcrypt.h>
 #include <glib.h>
 #include <gvm/base/logging.h>
+#include <stddef.h>
 #include <stdlib.h>
 
 #ifndef uchar
@@ -276,83 +278,6 @@ nasl_get_sign (lex_ctxt *lexic)
   return retc;
 }
 
-static void *
-hmac_md5_for_prf (const void *key, int keylen, const void *buf, int buflen)
-{
-  void *signature = g_malloc0 (16);
-  gsize signlen = 16;
-  GHmac *hmac;
-
-  hmac = g_hmac_new (G_CHECKSUM_MD5, key, keylen);
-  g_hmac_update (hmac, buf, buflen);
-  g_hmac_get_digest (hmac, signature, &signlen);
-  g_hmac_unref (hmac);
-  return signature;
-}
-
-static void *
-hmac_sha1 (const void *key, int keylen, const void *buf, int buflen)
-{
-  void *signature = g_malloc0 (20);
-  gsize signlen = 20;
-  GHmac *hmac;
-
-  hmac = g_hmac_new (G_CHECKSUM_SHA1, key, keylen);
-  g_hmac_update (hmac, buf, buflen);
-  g_hmac_get_digest (hmac, signature, &signlen);
-  g_hmac_unref (hmac);
-  return signature;
-}
-
-static void *
-hmac_sha256 (const void *key, int keylen, const void *buf, int buflen)
-{
-  void *signature = g_malloc0 (32);
-  gsize signlen = 32;
-  GHmac *hmac;
-
-  hmac = g_hmac_new (G_CHECKSUM_SHA256, key, keylen);
-  g_hmac_update (hmac, buf, buflen);
-  g_hmac_get_digest (hmac, signature, &signlen);
-  g_hmac_unref (hmac);
-  return signature;
-}
-
-static void *
-hmac_sha384 (const void *key, int keylen, const void *buf, int buflen)
-{
-  gcry_md_hd_t hd;
-  gcry_error_t err;
-  void *ret;
-
-  if (!buf || buflen <= 0)
-    return NULL;
-
-  err = gcry_md_open (&hd, GCRY_MD_SHA384, key ? GCRY_MD_FLAG_HMAC : 0);
-  if (err)
-    {
-      g_message ("nasl_gcrypt_hash(): gcry_md_open failed: %s/%s",
-                 gcry_strsource (err), gcry_strerror (err));
-      return NULL;
-    }
-
-  if (key)
-    {
-      err = gcry_md_setkey (hd, key, keylen);
-      if (err)
-        {
-          g_message ("nasl_gcrypt_hash(): gcry_md_setkey failed: %s/%s",
-                     gcry_strsource (err), gcry_strerror (err));
-          return NULL;
-        }
-    }
-
-  gcry_md_write (hd, buf, buflen);
-  ret = g_memdup2 (gcry_md_read (hd, 0), 48);
-  gcry_md_close (hd);
-  return ret;
-}
-
 tree_cell *
 nasl_hmac_sha256 (lex_ctxt *lexic)
 {
@@ -581,38 +506,19 @@ nasl_hmac_sha512 (lex_ctxt *lexic)
 tree_cell *
 nasl_get_smb2_sign (lex_ctxt *lexic)
 {
-  void *key, *buf, *signature, *ret;
-  int keylen, buflen;
-  tree_cell *retc;
-
-  key = get_str_var_by_name (lexic, "key");
-  buf = get_str_var_by_name (lexic, "buf");
-  keylen = get_var_size_by_name (lexic, "key");
-  buflen = get_var_size_by_name (lexic, "buf");
-  if (!key || !buf || keylen <= 0)
-    {
-      nasl_perror (lexic, "Syntax : get_smb2_signature(buf:<b>, key:<k>)");
-      return NULL;
-    }
-  if (buflen < 64)
-    {
-      nasl_perror (lexic, "get_smb2_sign: Buffer length < 64");
-      return NULL;
-    }
+  return nasl_smb_sign (G_CHECKSUM_SHA256, lexic);
+}
 
-  /* Zero the SMB2 signature field, then calculate signature */
-  memset ((char *) buf + 48, 0, 16);
-  signature = hmac_sha256 (key, keylen, buf, buflen);
+tree_cell *
+nasl_smb_cmac_aes_sign (lex_ctxt *lexic)
+{
+  return nasl_smb_sign (GCRY_MAC_CMAC_AES, lexic);
+}
 
-  /* Return the header with signature included. */
-  ret = g_malloc0 (buflen);
-  memcpy (ret, buf, buflen);
-  memcpy ((char *) ret + 48, signature, 16);
-  g_free (signature);
-  retc = alloc_typed_cell (CONST_DATA);
-  retc->size = buflen;
-  retc->x.str_val = (char *) ret;
-  return retc;
+tree_cell *
+nasl_smb_gmac_aes_sign (lex_ctxt *lexic)
+{
+  return nasl_smb_sign (GCRY_MAC_GMAC_AES, lexic);
 }
 
 tree_cell *

diff --git a/nasl/nasl_crypto.h b/nasl/nasl_crypto.h
@@ -123,6 +123,12 @@ nasl_get_sign (lex_ctxt *lexic);
 tree_cell *
 nasl_get_smb2_sign (lex_ctxt *lexic);
 
+tree_cell *
+nasl_smb_cmac_aes_sign (lex_ctxt *lexic);
+
+tree_cell *
+nasl_smb_gmac_aes_sign (lex_ctxt *lexic);
+
 tree_cell *
 nasl_hmac_sha256 (lex_ctxt *lexic);