Fix weak random number hole

Obtained from: CERT

eBones/README.PATCH

@@ -0,0 +1,60 @@
+READ THIS ENTIRE FILE BEFORE PROCEEDING!
+
+This distribution contains a "diff" file suitable for using with the
+"patch" program to update your Kerberos (version 4) source tree. The
+gist of the patch is to replace calls to des_random_key() with calls
+to des_new_random_key().
+
+The primary difference is that des_random_key() uses a seeding
+technique which is predictable and therefore
+vulnerable. des_new_random_key() uses a feedback mechanism based on
+the Data Encryption Standard (DES) and is seeded with a secret (and
+therefore unknown to an attacker) value. This value is the database
+master key, which is a convenient secret value.
+
+This patch assumes that you have the new_rnd_key.c key module (which
+contains the definition and code for des_new_random_key()). It has
+been part of the standard Version 4 distribution since 1992 and is
+used in the admin server (our primary error at MIT was not upgrading
+all of Kerberos to use this newer generator. This patch finishes the
+job).
+
+In addition to the patch file for the Kerberos distribution this
+distribution also contains a program for changing critical system keys
+(namely the "krbtgt" and "changepw.kerberos" keys). When you
+originally built your Kerberos database these keys were chosen at
+random, using the vulnerable version of the kerberos random number
+generator. Therefore it is possible for an attacker to mount an attack
+to guess these values. If an attacker can determine the key for the
+"krbtgt" ticket, they can construct tickets claiming to be any
+kerberos principal. Similarly if an attacker can obtain the
+"changepw.kerberos" key, they can change anyone's password.
+
+The enclosed "fix_kdb_keys.c" (part of the patch file) program, which
+you run on the KDC server, will change these critical keys to new
+values using the newer random number generator. IMPORTANT: When you
+run fix_kdb_keys, all outstanding ticket granting tickets will
+immediately become invalid. This will be disruptive to your user
+community. We recommend that you either do this late at night or early
+in the morning before most users have logged in. Alternatively
+pre-announce a definitive time when you will run the program and
+inform your users that they will have to get new tickets at that time
+(using either "kinit" or simply by logging out and then in again).
+
+NOTE: The only client program modified is "ksrvutil" which is used to
+generate new server keys. All other client/server programs are
+unaffected. End users do *not* need to obtain new versions of programs
+that use Kerberos. This is because most random number generation in
+the Kerberos system is done on the KDC system. By fixing kerberos.c
+you have repaired most of the damage.
+
+To install this patch copy patch_krb to the toplevel of your Kerberos
+source tree. Then type:
+
+patch -p0 <patch_krb
+
+This will install changes to various kerberos modules to upgrade them
+to use des_new_random_key(). It also will install a new program,
+"fix_kdb_keys.c." After the patch is complete type "make world" at the
+toplevel of your Kerberos source tree. This will, among other things,
+build the fix_kdb_keys program.

eBones/usr.sbin/Makefile

@@ -1,7 +1,7 @@
 #	From: @(#)Makefile	5.1 (Berkeley) 6/25/90
-#	$Id$
+#	$Id: Makefile,v 1.1 1995/09/13 17:24:15 markm Exp $
 
-SUBDIR=	ext_srvtab kadmind kdb_destroy kdb_edit kdb_init kdb_util \
-	kerberos kprop ksrvutil kstash make_keypair
+SUBDIR= ext_srvtab fix_kdb_keys kadmind kdb_destroy kdb_edit kdb_init \
+	kdb_util kerberos kprop ksrvutil kstash make_keypair
 
 .include <bsd.subdir.mk>

eBones/usr.sbin/fix_kdb_keys/Makefile

@@ -0,0 +1,10 @@
+#	From: @(#)Makefile	5.2 (Berkeley) 3/5/91
+#	$Id: Makefile,v 1.7 1995/09/26 06:20:18 mark Exp $
+
+PROG=   fix_kdb_keys
+CFLAGS+=-DKERBEROS -DDEBUG
+DPADD=	${LIBKDB} ${LIBKRB} ${LIBDES}
+LDADD=	-L${KDBOBJDIR} -lkdb -L${KRBOBJDIR} -lkrb -L${DESOBJDIR} -ldes
+NOMAN=  YES
+
+.include <bsd.prog.mk>

eBones/usr.sbin/fix_kdb_keys/fix_kdb_keys.c

@@ -0,0 +1,191 @@
+/*
+ * $Source: /afs/net/project/krb4/src/admin/RCS/kdb_edit.c,v $
+ * $Author: tytso $
+ *
+ * Copyright 1985, 1986, 1987, 1988 by the Massachusetts Institute
+ * of Technology.
+ *
+ * For copying and distribution information, please see the file
+ * <mit-copyright.h>.
+ *
+ * This routine changes the Kerberos encryption keys for principals,
+ * i.e., users or services. 
+ */
+
+/*
+ * exit returns 	 0 ==> success -1 ==> error 
+ */
+
+#include <stdio.h>
+#include <signal.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#include <sys/file.h>
+
+#ifdef NEED_TIME_H
+#include <time.h>
+#endif
+#include <sys/time.h>
+
+#include <des.h>
+#include <krb.h>
+#include <krb_db.h>
+/* MKEYFILE is now defined in kdc.h */
+#include <kdc.h>
+
+char    prog[32];
+char   *progname = prog;
+int     nflag = 0;
+int     debug = 0;
+extern  int krb_debug;
+
+Principal principal_data;
+
+static C_Block master_key;
+static Key_schedule master_key_schedule;
+static long master_key_version;
+
+static char realm[REALM_SZ];
+
+void fatal_error(), cleanup();
+void Usage();
+void change_principal();
+
+int main(argc, argv)
+     int     argc;
+     char   *argv[];
+{
+  int i;
+
+  prog[sizeof prog - 1] = '\0';	/* make sure terminated */
+  strncpy(prog, argv[0], sizeof prog - 1);	/* salt away invoking
+						 * program */
+
+  /* Assume a long is four bytes */
+  if (sizeof(long) != 4) {
+    fprintf(stderr, "%s: size of long is %d.\n", prog, sizeof(long));
+    exit(-1);
+  }
+  while (--argc > 0 && (*++argv)[0] == '-')
+    for (i = 1; argv[0][i] != '\0'; i++) {
+      switch (argv[0][i]) {
+	
+	/* debug flag */
+      case 'd':
+	debug = 1;
+	continue;
+
+	/* debug flag */
+      case 'l':
+	krb_debug |= 1;
+	continue;
+
+      case 'n':		/* read MKEYFILE for master key */
+	nflag = 1;
+	continue;
+	
+      default:
+	fprintf(stderr, "%s: illegal flag \"%c\"\n", progname, argv[0][i]);
+	Usage();	/* Give message and die */
+      }
+    };
+
+  if (krb_get_lrealm(realm, 1)) {
+	  fprintf(stderr, "Couldn't get local realm information.\n");
+	  fatal_error();
+  }
+
+  kerb_init();
+  if (argc > 0) {
+    if (kerb_db_set_name(*argv) != 0) {
+      fprintf(stderr, "Could not open altername database name\n");
+      fatal_error();
+    }
+  }
+
+  if (kdb_get_master_key ((nflag == 0), 
+			  master_key, master_key_schedule) != 0) {
+    fprintf (stderr, "Couldn't read master key.\n");
+    fatal_error();
+  }
+
+  if ((master_key_version = kdb_verify_master_key(master_key,
+						  master_key_schedule,
+						  stdout)) < 0)
+	  fatal_error();
+
+  des_init_random_number_generator(master_key);
+
+  change_principal("krbtgt", realm);
+  change_principal("changepw", KRB_MASTER);
+
+  cleanup();
+
+  printf("\nKerberos database updated successfully.  Note that all\n");
+  printf("existing ticket-granting tickets have been invalidated.\n\n");
+
+  return(0);
+}
+
+void change_principal(input_name, input_instance)
+     char *input_name;
+     char *input_instance;
+{
+    int     n, more;
+    C_Block new_key;
+
+    n = kerb_get_principal(input_name, input_instance, &principal_data,
+			   1, &more);
+    if (!n) {
+      fprintf(stderr, "Can't find principal database for %s.%s.\n", 
+	      input_name, input_instance);
+      fatal_error();
+    }
+    if (more) {
+      fprintf(stderr, "More than one entry for %s.%s.\n", input_name, 
+	      input_instance);
+      fatal_error();
+    }
+      
+    des_new_random_key(new_key);
+
+    /* seal it under the kerberos master key */
+    kdb_encrypt_key (new_key, new_key, 
+		     master_key, master_key_schedule,
+				 ENCRYPT);
+    memcpy(&principal_data.key_low, new_key, 4);
+    memcpy(&principal_data.key_high, ((long *) new_key) + 1, 4);
+    memset(new_key, 0, sizeof(new_key));
+
+    principal_data.key_version++;
+
+    if (kerb_put_principal(&principal_data, 1)) {
+      fprintf(stderr, "\nError updating Kerberos database");
+      fatal_error();
+    }
+
+    memset(&principal_data.key_low, 0, 4);
+    memset(&principal_data.key_high, 0, 4);
+}
+
+void fatal_error()
+{
+	cleanup();
+	exit(1);
+}
+
+void cleanup()
+{
+
+  memset(master_key, 0, sizeof(master_key));
+  memset(master_key_schedule, 0, sizeof(master_key_schedule));
+  memset(&principal_data, 0, sizeof(principal_data));
+}
+
+void Usage()
+{
+    fprintf(stderr, "Usage: %s [-n]\n", progname);
+    exit(1);
+}

eBones/usr.sbin/kdb_edit/kdb_edit.c

@@ -8,7 +8,7 @@
  * i.e., users or services.
  *
  *	from: kdb_edit.c,v 4.2 90/01/09 16:05:09 raeburn Exp $
- *	$Id: kdb_edit.c,v 1.5 1995/08/03 17:15:54 mark Exp $
+ *	$Id: kdb_edit.c,v 1.5 1995/09/07 21:37:17 markm Exp $
  */
 
 /*
@@ -18,7 +18,7 @@
 #if 0
 #ifndef	lint
 static char rcsid[] =
-"$Id: kdb_edit.c,v 1.5 1995/08/03 17:15:54 mark Exp $";
+"$Id: kdb_edit.c,v 1.5 1995/09/07 21:37:17 markm Exp $";
 #endif	lint
 #endif
 
@@ -173,6 +173,8 @@ main(argc, argv)
 						    stdout)) < 0)
       exit (-1);
 
+    des_init_random_number_generator(master_key);
+
     /* lookup the default values */
     n = kerb_get_principal(KERB_DEFAULT_NAME, KERB_DEFAULT_INST,
 			   &default_princ, 1, &more);
@@ -282,7 +284,7 @@ change_principal()
 			bzero(new_key, sizeof(C_Block));
 			new_key[0] = 127;
 #else
-			random_key(new_key);
+			des_new_random_key(new_key);    /* yes, random */
 #endif
 			bzero(pw_str, sizeof pw_str);
 		    }

eBones/usr.sbin/kdb_init/kdb_init.c

@@ -7,13 +7,13 @@
  * already exists.
  *
  *	from: kdb_init.c,v 4.0 89/01/24 21:50:45 jtkohl Exp $
- *	$Id: kdb_init.c,v 1.4 1995/07/18 16:37:35 mark Exp $
+ *	$Id: kdb_init.c,v 1.4 1995/09/07 21:37:20 markm Exp $
  */
 
 #if 0
 #ifndef	lint
 static char rcsid[] =
-"$Id: kdb_init.c,v 1.4 1995/07/18 16:37:35 mark Exp $";
+"$Id: kdb_init.c,v 1.4 1995/09/07 21:37:20 markm Exp $";
 #endif	lint
 #endif
 
@@ -97,6 +97,7 @@ main(argc, argv)
       fprintf (stderr, "Couldn't read master key.\n");
       exit (-1);
     }
+    des_init_random_number_generator(master_key);
 
     if (
 	add_principal(KERB_M_NAME, KERB_M_INST, MASTER_KEY) ||
@@ -140,7 +141,7 @@ add_principal(name, instance, aap_op)
 	bzero(new_key, sizeof(C_Block));
 	new_key[0] = 127;
 #else
-	random_key(new_key);
+	des_new_random_key(new_key);
 #endif
 	kdb_encrypt_key (new_key, new_key, master_key, master_key_schedule,
 			 ENCRYPT);

eBones/usr.sbin/kerberos/kerberos.c

@@ -5,13 +5,13 @@
  * <Copyright.MIT>.
  *
  *	from: kerberos.c,v 4.19 89/11/01 17:18:07 qjb Exp $
- *	$Id: kerberos.c,v 1.4 1995/09/07 21:37:27 markm Exp $
+ *	$Id: kerberos.c,v 1.5 1995/09/17 00:39:00 gibbs Exp $
  */
 
 #if 0
 #ifndef lint
 static char rcsid[] =
-"$Id: kerberos.c,v 1.4 1995/09/07 21:37:27 markm Exp $";
+"$Id: kerberos.c,v 1.5 1995/09/17 00:39:00 gibbs Exp $";
 #endif  lint
 #endif
 
@@ -269,6 +269,7 @@ main(argc, argv)
       bzero (master_key_schedule, sizeof (master_key_schedule));
       exit (-1);
     }
+    des_init_random_number_generator(master_key);
 
     master_key_version = (u_char) kerror;
 
@@ -434,7 +435,7 @@ kerberos(client, pkt)
 #ifdef NOENCRYPTION
 	    bzero(session_key, sizeof(C_Block));
 #else
-	    random_key(session_key);
+	    des_new_random_key(session_key);
 #endif
 	    /* unseal server's key from master key */
 	    bcopy(&s_name_data.key_low, key, 4);
@@ -565,7 +566,7 @@ kerberos(client, pkt)
 #ifdef NOENCRYPTION
 	    bzero(session_key, sizeof(C_Block));
 #else
-	    random_key(session_key);
+	    des_new_random_key(session_key);
 #endif
 
 	    krb_create_ticket(tk, k_flags, ad->pname, ad->pinst,

eBones/usr.sbin/ksrvutil/ksrvutil.c

@@ -12,7 +12,7 @@
 static char rcsid_ksrvutil_c[] =
 "BonesHeader: /afs/athena.mit.edu/astaff/project/kerberos/src/kadmin/RCS/ksrvutil.c,v 4.1 89/09/26 09:33:49 jtkohl Exp ";
 static const char rcsid[] =
-	"$Id: ksrvutil.c,v 1.1 1995/07/18 16:40:11 mark Exp $";
+	"$Id: ksrvutil.c,v 1.5 1995/09/07 21:38:40 markm Exp $";
 #endif	lint
 #endif
 
@@ -523,16 +523,20 @@ get_svc_new_key(new_key, sname, sinst, srealm, keyfile)
   char *keyfile;
 {
     int status = KADM_SUCCESS;
+    CREDENTIALS c;
 
     if (((status = krb_get_svc_in_tkt(sname, sinst, srealm, PWSERV_NAME,
 				      KADM_SINST, 1, keyfile)) == KSUCCESS) &&
+	((status = krb_get_cred(PWSERV_NAME, KADM_SINST, srealm, &c)) ==
+	 KSUCCESS) &&
 	((status = kadm_init_link("changepw", KRB_MASTER, srealm)) ==
 	 KADM_SUCCESS)) {
 #ifdef NOENCRYPTION
 	bzero((char *) new_key, sizeof(des_cblock));
 	new_key[0] = (unsigned char) 1;
 #else /* NOENCRYPTION */
-	des_random_key(new_key);
+	des_init_random_number_generator(c.session);
+	(void) des_new_random_key(new_key);
 #endif /* NOENCRYPTION */
 	return(KADM_SUCCESS);
     }