From: Harlan Stenn <stenn@ntp.org>
Date: Fri, 27 May 2016 05:37:19 +0000 (-0700)
Subject: [Sec3043] - validate origin timestamps on bad MACs, too.  stenn@ntp.org
X-Git-Tag: NTP_4_2_8P8~4
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2e38c41cad6da138b463f0990f8276e78273d201;p=thirdparty%2Fntp.git

[Sec3043] - validate origin timestamps on bad MACs, too.  stenn@ntp.org

bk: 5747dd0fk9FN_tD9dhCQXHL8TNSdWw
---

diff --git a/ChangeLog b/ChangeLog
index 05fd404d5..4fdad3d64 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,8 +2,9 @@
 
 * [Sec 3042] Broadcast Interleave.  HStenn.
 * [Sec 3043] Autokey association reset.  perlinger@ntp.org, stenn@ntp.org
-  - fixes [Sec 3044] (partially) and [Sec 3045], too.
+  - validate origin timestamps on bad MACs, too.  stenn@ntp.org
 * [Sec 3044] Spoofed server packets are partially processed.  HStenn.
+* [Sec 3045] Bad authentication demobilizes ephemeral associations. JPerlinger.
 * [Sec 3046] CRYPTO_NAK crash.  stenn@ntp.org
 * [Bug 3038] NTP fails to build in VS2015. perlinger@ntp.org
   - provide build environment
diff --git a/NEWS b/NEWS
index 17aef6071..6d841198a 100644
--- a/NEWS
+++ b/NEWS
@@ -10,7 +10,7 @@ following 1 high- and 4 low-severity vulnerabilities"
 
 * CRYPTO_NAK crash
    Date Resolved: 02 June 2016; Dev (4.3.93) 02 June 2016
-   References: Sec 3046 / CVE-2016-4957 / VU#BBBBB
+   References: Sec 3046 / CVE-2016-4957 / VU#321640
    Affects: ntp-4.2.8p7, and ntp-4.3.92.
    CVSS2: HIGH 7.8 (AV:N/AC:L/Au:N/C:N/I:N/A:C)
    CVSS3: HIGH 7.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
@@ -28,7 +28,7 @@ following 1 high- and 4 low-severity vulnerabilities"
 
 * Bad authentication demobilizes ephemeral associations
    Date Resolved: 02 June 2016; Dev (4.3.93) 02 June 2016
-   References: Sec 3045 / CVE-2016-4953
+   References: Sec 3045 / CVE-2016-4953 / VU#321640
    Affects: ntp-4, up to but not including ntp-4.2.8p8, and
 	ntp-4.3.0 up to, but not including ntp-4.3.93.
    CVSS2: LOW 2.6 (AV:N/AC:H/Au:N/C:N/I:N/A:P)
@@ -46,7 +46,7 @@ following 1 high- and 4 low-severity vulnerabilities"
 
 * Processing spoofed server packets
    Date Resolved: 02 June 2016; Dev (4.3.93) 02 June 2016
-   References: Sec 3044 / CVE-2016-4954
+   References: Sec 3044 / CVE-2016-4954 / VU#321640
    Affects: ntp-4, up to but not including ntp-4.2.8p8, and
 	ntp-4.3.0 up to, but not including ntp-4.3.93.
    CVSS2: LOW 2.6 (AV:N/AC:H/Au:N/C:N/I:N/A:P)
@@ -60,20 +60,20 @@ following 1 high- and 4 low-severity vulnerabilities"
 	Upgrade to 4.2.8p8, or later, from the NTP Project Download Page
 	    or the NTP Public Services Project Download Page
 	Properly monitor your ntpd instances. 
-   Credit: This weakness was discovered by Miroslav Lichvar of Red Hat. 
+   Credit: This weakness was discovered by Jakub Prokes of Red Hat. 
 
 * Autokey association reset
    Date Resolved: 02 June 2016; Dev (4.3.93) 02 June 2016
-   References: Sec 3043 / CVE-2016-4955
+   References: Sec 3043 / CVE-2016-4955 / VU#321640
    Affects: ntp-4, up to but not including ntp-4.2.8p8, and
 	ntp-4.3.0 up to, but not including ntp-4.3.93.
    CVSS2: LOW 2.6 (AV:N/AC:H/Au:N/C:N/I:N/A:P)
    CVSS3: LOW 3.7 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
    Summary: An attacker who is able to spoof a packet with a correct
 	origin timestamp before the expected response packet arrives at
-	the target machine can send a CRYPTO_NAK and cause the
-	association's peer variables to be cleared. If this can be done
-	often enough, it will prevent that association from working.
+	the target machine can send a CRYPTO_NAK or a bad MAC and cause
+	the association's peer variables to be cleared. If this can be
+	done often enough, it will prevent that association from working.
    Mitigation:
 	Implement BCP-38.
 	Upgrade to 4.2.8p8, or later, from the NTP Project Download Page
@@ -83,7 +83,7 @@ following 1 high- and 4 low-severity vulnerabilities"
  
 * Broadcast interleave
    Date Resolved: 02 June 2016; Dev (4.3.93) 02 June 2016
-   References: Sec 3042 / CVE-2016-4956
+   References: Sec 3042 / CVE-2016-4956 / VU#321640
    Affects: ntp-4, up to but not including ntp-4.2.8p8, and
    	ntp-4.3.0 up to, but not including ntp-4.3.93.
    CVSS2: LOW 2.6 (AV:N/AC:H/Au:N/C:N/I:N/A:P)
diff --git a/ntpd/ntp_proto.c b/ntpd/ntp_proto.c
index 7809fb4a3..513b99f68 100644
--- a/ntpd/ntp_proto.c
+++ b/ntpd/ntp_proto.c
@@ -1682,8 +1682,9 @@ receive(
 	/*
 	 * Check for valid nonzero timestamp fields.
 	 */
-	} else if (L_ISZERO(&p_org) || L_ISZERO(&p_rec) ||
-	    L_ISZERO(&peer->dst)) {
+	} else if (   L_ISZERO(&p_org)
+		   || L_ISZERO(&p_rec)
+		   || L_ISZERO(&peer->dst)) {
 		peer->flash |= TEST3;		/* unsynch */
 
 	/*
@@ -1699,6 +1700,8 @@ receive(
 		return; /* Bogus packet, we are done */
 	}
 
+	/**/
+
 	/*
 	 * If this is a crypto_NAK, the server cannot authenticate a
 	 * client packet. The server might have just changed keys. Clear
@@ -1715,8 +1718,9 @@ receive(
 			return;
 		}
 #ifdef AUTOKEY
-		if (peer->crypto)
+		if (peer->crypto) {
 			peer_clear(peer, "AUTH");
+		}
 #endif	/* AUTOKEY */
 		return;
 
@@ -1730,21 +1734,30 @@ receive(
 	 */
 	} else if (!AUTH(peer->keyid || has_mac ||
 			 (restrict_mask & RES_DONTTRUST), is_authentic)) {
+
+		if (peer->flash & PKT_TEST_MASK) {
+			msyslog(LOG_INFO,
+				"receive: Bad auth in packet with bad timestamps from %s denied - spoof?",
+				ntoa(&peer->srcadr));
+			return;
+		}
+
 		report_event(PEVNT_AUTH, peer, "digest");
 		peer->flash |= TEST5;		/* bad auth */
 		peer->badauth++;
 		if (   has_mac
-		    && (hismode == MODE_ACTIVE || hismode == MODE_PASSIVE))
+		    && (   hismode == MODE_ACTIVE
+			|| hismode == MODE_PASSIVE))
 			fast_xmit(rbufp, MODE_ACTIVE, 0, restrict_mask);
 		if (peer->flags & FLAG_PREEMPT) {
 			if (unpeer_digest_early) {
 				unpeer(peer);
 			}
-			return;
 		}
 #ifdef AUTOKEY
-		if (peer_clear_digest_early && peer->crypto)
+		else if (peer_clear_digest_early && peer->crypto) {
 			peer_clear(peer, "AUTH");
+		}
 #endif	/* AUTOKEY */
 		return;
 	}