Cisco Applied Mitigation Bulletin-
Vulnerability Characteristics
The Cisco Unified Presence and Jabber Extensible Communications Platform (Jabber XCP) contain a vulnerability when processing a specially crafted Extensible Messaging and Presence Protocol (XMPP) stream header using IP version 4 (IPv4) or IP version 6 (IPv6). This vulnerability can be exploited remotely without authentication and without end-user interaction. Successful exploitation of this vulnerability could result in a denial of service (DoS) condition. Repeated attempts to exploit this vulnerability could result in a sustained DoS condition. The attack vector for exploitation is through XMPP IPv4 and IPv6 packets using TCP port 5222 by default.
This vulnerability has been assigned Common Vulnerabilities and Exposures (CVE) identifier CVE-2012-3935.
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Information about vulnerable, unaffected, and fixed software is available in the Cisco Security Advisory, which is available at the following link: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20120912-cupxcp.
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Cisco devices provide several countermeasures for this vulnerability. Administrators are advised to consider these protection methods to be general security best practices for infrastructure devices and the traffic that transits the network. This section of the document provides an overview of these techniques.
Cisco IOS Software can provide effective means of exploit prevention using transit access control lists (tACLs).
This protection mechanism filters and drops packets that are attempting to exploit this vulnerability.
Effective exploit prevention can also be provided by the Cisco ASA 5500 Series Adaptive Security Appliance, Cisco Catalyst 6500 Series ASA Services Module (ASASM), and the Firewall Services Module (FWSM) for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers using tACLs.
This protection mechanism filters and drops packets that are attempting to exploit this vulnerability.
Cisco IOS NetFlow records can provide visibility into network-based exploitation attempts.
Cisco IOS Software, Cisco ASA, Cisco ASASM, and Cisco FWSM firewalls can provide visibility through syslog messages and counter values displayed in the output from show commands.
The Cisco Security Manager can also provide visibility through incidents, queries, and event reporting.
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Organizations are advised to follow their standard risk evaluation and mitigation processes to determine the potential impact of this vulnerability. Triage refers to sorting projects and prioritizing efforts that are most likely to be successful. Cisco has provided documents that can help organizations develop a risk-based triage capability for their information security teams. Risk Triage for Security Vulnerability Announcements and Risk Triage and Prototyping can help organizations develop repeatable security evaluation and response processes.
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Caution: The effectiveness of any mitigation technique depends on specific customer situations such as product mix, network topology, traffic behavior, and organizational mission. As with any configuration change, evaluate the impact of this configuration prior to applying the change.
Specific information about mitigation and identification is available for these devices:
- Cisco IOS Routers and Switches
- Cisco IOS NetFlow and Cisco IOS Flexible NetFlow
- Cisco ASA, Cisco ASASM, and Cisco FWSM Firewalls
- Cisco Security Manager
Cisco IOS Routers and Switches
Mitigation: Transit Access Control Lists
To protect the network from traffic that enters the network at ingress access points, which may include Internet connection points, partner and supplier connection points, or VPN connection points, administrators are advised to deploy transit access control lists (tACLs) to perform policy enforcement. Administrators can construct a tACL by explicitly permitting only authorized traffic to enter the network at ingress access points or permitting authorized traffic to transit the network in accordance with existing security policies and configurations. A tACL workaround cannot provide complete protection against this vulnerability when the attack originates from a trusted source address.
The tACL policy denies unauthorized IPv4 and IPv6 packets on TCP port 5222 that are sent to affected devices. In the following example, 192.168.60.0/24 and 2001:DB8:1:60::/64 represent the IP address space that is used by the affected devices, and the hosts at 192.168.100.1 and 2001:DB8::100:1 are considered trusted sources that require access to the affected devices. Care should be taken to allow required traffic for routing and administrative access prior to denying all unauthorized traffic.
Additional information about tACLs is in Transit Access Control Lists: Filtering at Your Edge.
! !-- Include explicit permit statements for trusted sources !-- that require access on the vulnerable TCP port ! access-list 150 permit tcp host 192.168.100.1 192.168.60.0 0.0.0.255 eq 5222 ! !-- The following vulnerability-specific access control entry !-- (ACE) can aid in identification of attacks ! access-list 150 deny tcp any 192.168.60.0 0.0.0.255 eq 5222 ! !-- Permit or deny all other Layer 3 and Layer 4 traffic in accordance !-- with existing security policies and configurations ! !-- Explicit deny for all other IP traffic ! access-list 150 deny ip any any ! !-- Create the corresponding IPv6 tACL ! ipv6 access-list IPv6-Transit-ACL-Policy ! !-- Include explicit permit statements for trusted sources !-- that require access on the vulnerable TCP port ! permit tcp host 2001:DB8::100:1 2001:DB8:1:60::/64 eq 5222 ! !-- The following vulnerability-specific ACE can !-- aid in identification of attacks to global and !-- link-local addresses ! deny tcp any 2001:DB8:1:60::/64 eq 5222 ! !-- Permit or deny all other Layer 3 and Layer 4 traffic in !-- accordance with existing security policies and configurations !-- and allow IPv6 neighbor discovery packets, which !-- include neighbor solicitation packets and neighbor !-- advertisement packets ! permit icmp any any nd-ns permit icmp any any nd-na !
!-- Explicit deny for all other IPv6 traffic !
deny ipv6 any any ! ! !-- Apply tACLs to interfaces in the ingress direction ! interface GigabitEthernet0/0 ip access-group 150 in ipv6 traffic-filter IPv6-Transit-ACL-Policy inNote that filtering with an interface access list will elicit the transmission of ICMP unreachable messages back to the source of the filtered traffic. Generating these messages could have the undesired effect of increasing CPU utilization on the device. In Cisco IOS Software, ICMP unreachable generation is limited to one packet every 500 milliseconds by default. ICMP unreachable message generation can be disabled using the interface configuration commands no ip unreachables and no ipv6 unreachables. ICMP unreachable rate limiting can be changed from the default using the global configuration commands ip icmp rate-limit unreachable interval-in-ms and ipv6 icmp error-interval interval-in-ms.
Identification: Transit Access Control Lists
After the administrator applies the tACL to an interface, show ip access-lists and show ipv6 access-list commands will identify the number of XMPP IPv4 and IPv6 packets on TCP port 5222 that have been filtered. Administrators are advised to investigate filtered packets to determine whether they are attempts to exploit this vulnerability. Example output for show ip access-lists 150 and show ipv6 access-list IPv6-Transit-ACL-Policy follows:
router#show ip access-lists 150 Extended IP access list 150 10 permit tcp host 192.168.100.1 192.168.60.0 0.0.0.255 eq 5222 20 deny tcp any 192.168.60.0 0.0.0.255 eq 5222 (42 matches) 30 deny ip any any router#In the preceding example, access list 150 has dropped 42 XMPP packets on TCP port 5222 for access control list entry (ACE) line 20.
router#show ipv6 access-list IPv6-Transit-ACL-Policy IPv6 access list IPv6-Transit-ACL-Policy permit tcp host 2001:DB8::100:1 2001:DB8:1:60::/64 eq 5222 (55 matches) sequence 10 deny tcp any 2001:DB8:1:60::/64 eq 5222 (30 matches) sequence 20 permit icmp any any nd-ns (41 matches) sequence 30 permit icmp any any nd-na (41 matches) sequence 40 deny ipv6 any any (21 matches) sequence 50In the preceding example, access list IPv6-Transit-ACL-Policy has dropped 30 XMPP packets on TCP port 5222 for access control list entry (ACE) line 20.
For additional information about investigating incidents using ACE counters and syslog events, reference the Identifying Incidents Using Firewall and IOS Router Syslog Events Cisco Security Intelligence Operations white paper.
Administrators can use Embedded Event Manager to provide instrumentation when specific conditions are met, such as ACE counter hits. The Cisco Security Intelligence Operations white paper Embedded Event Manager in a Security Context provides additional details about how to use this feature.
Identification: Access List Logging
The log and log-input access control list (ACL) option will cause packets that match specific ACEs to be logged. The log-input option enables logging of the ingress interface in addition to the packet source and destination IP addresses and ports.
Caution: Access control list logging can be very CPU intensive and must be used with extreme caution. Factors that drive the CPU impact of ACL logging are log generation, log transmission, and process switching to forward packets that match log-enabled ACEs.
For Cisco IOS Software, the ip access-list logging interval interval-in-ms command can limit the effects of process switching induced by IPv4 ACL logging. The logging rate-limit rate-per-second [except loglevel] command limits the impact of log generation and transmission.
The CPU impact from ACL logging can be addressed in hardware on the Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers with Supervisor Engine 720 or Supervisor Engine 32 using optimized ACL logging.
For additional information about the configuration and use of ACL logging, reference the Understanding Access Control List Logging Cisco Security white paper.
Cisco IOS NetFlow and Cisco IOS Flexible NetFlow
Identification: IPv4 Traffic Flow Identification Using Cisco IOS NetFlow
Administrators can configure Cisco IOS NetFlow on Cisco IOS routers and switches to aid in the identification of IPv4 traffic flows that may be attempts to exploit this vulnerability. Administrators are advised to investigate flows to determine whether they are attempts to exploit this vulnerability or whether they are legitimate traffic flows.
router#show ip cache flow IP packet size distribution (90784136 total packets): 1-32 64 96 128 160 192 224 256 288 320 352 384 416 448 480 .000 .698 .011 .001 .004 .005 .000 .004 .000 .000 .003 .000 .000 .000 .000 512 544 576 1024 1536 2048 2560 3072 3584 4096 4608 .000 .001 .256 .000 .010 .000 .000 .000 .000 .000 .000 IP Flow Switching Cache, 4456704 bytes 1885 active, 63651 inactive, 59960004 added 129803821 ager polls, 0 flow alloc failures Active flows timeout in 30 minutes Inactive flows timeout in 15 seconds IP Sub Flow Cache, 402056 bytes 0 active, 16384 inactive, 0 added, 0 added to flow 0 alloc failures, 0 force free 1 chunk, 1 chunk added last clearing of statistics never Protocol Total Flows Packets Bytes Packets Active(Sec) Idle(Sec) -------- Flows /Sec /Flow /Pkt /Sec /Flow /Flow TCP-Telnet 11393421 2.8 1 48 3.1 0.0 1.4 TCP-FTP 236 0.0 12 66 0.0 1.8 4.8 TCP-FTPD 21 0.0 13726 1294 0.0 18.4 4.1 TCP-WWW 22282 0.0 21 1020 0.1 4.1 7.3 TCP-X 719 0.0 1 40 0.0 0.0 1.3 TCP-BGP 1 0.0 1 40 0.0 0.0 15.0 TCP-Frag 70399 0.0 1 688 0.0 0.0 22.7 TCP-other 47861004 11.8 1 211 18.9 0.0 1.3 UDP-DNS 582 0.0 4 73 0.0 3.4 15.4 UDP-NTP 287252 0.0 1 76 0.0 0.0 15.5 UDP-other 310347 0.0 2 230 0.1 0.6 15.9 ICMP 11674 0.0 3 61 0.0 19.8 15.5 IPv6INIP 15 0.0 1 1132 0.0 0.0 15.4 GRE 4 0.0 1 48 0.0 0.0 15.3 Total: 59957957 14.8 1 196 22.5 0.0 1.5 SrcIf SrcIPaddress DstIf DstIPaddress Pr SrcP DstP Pkts Gi0/0 192.168.10.201 Gi0/1 192.168.60.102 06 0984 1466 1 Gi0/0 192.168.11.54 Gi0/1 192.168.60.158 11 0911 00A1 3 Gi0/1 192.168.150.60 Gi0/0 10.89.16.226 11 0016 0035 1 Gi0/0 192.168.13.97 Gi0/1 192.168.60.28 06 0B3E 1466 5 Gi0/0 192.168.10.17 Gi0/1 192.168.60.97 06 0B89 1466 1 Gi0/0 10.88.226.1 Gi0/1 192.168.202.22 06 4652 0050 1 Gi0/0 192.168.12.185 Gi0/1 192.168.60.239 06 0BD7 0050 1 Gi0/0 10.89.16.226 Gi0/1 192.168.150.60 06 12CA 1466 1 router#In the preceding example, there are multiple flows for XMPP on TCP port 5222 (hex value 1466).
As shown in the following example, to view only the XMPP packets on TCP port 5222 (hex value 1466), use the show ip cache flow | include SrcIf|_06_.*1466 command to display the related Cisco NetFlow records:
TCP Flowsrouter#show ip cache flow | include SrcIf|_06_.*1466 SrcIf SrcIPaddress DstIf DstIPaddress Pr SrcP DstP Pkts Gi0/0 192.168.12.110 Gi0/1 192.168.60.163 06 9843 1466 88 Gi0/0 192.168.11.230 Gi0/1 192.168.60.20 06 9844 1466 21 Gi0/0 192.168.11.131 Gi0/1 192.168.60.245 06 9845 1466 18 Gi0/0 192.168.13.7 Gi0/1 192.168.60.162 06 9846 1466 61 router#
Identification: IPv6 Traffic Flow Identification Using Cisco IOS NetFlow
Administrators can configure Cisco IOS NetFlow on Cisco IOS routers and switches to aid in the identification of IPv6 traffic flows that may be attempts to exploit the vulnerability that is described in this document. Administrators are advised to investigate flows to determine whether they are attempts to exploit this vulnerability or whether they are legitimate traffic flows.
The following output is from a Cisco IOS device running Cisco IOS Software 12.4 mainline train. The command syntax will vary for different Cisco IOS Software trains.
router#show ipv6 flow cache IP packet size distribution (50078919 total packets): 1-32 64 96 128 160 192 224 256 288 320 352 384 416 448 480 .000 .990 .001 .008 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000
512 544 576 1024 1536 2048 2560 3072 3584 4096 4608 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000
IP Flow Switching Cache, 475168 bytes 8 active, 4088 inactive, 6160 added 1092984 ager polls, 0 flow alloc failures Active flows timeout in 30 minutes Inactive flows timeout in 15 seconds
IP Sub Flow Cache, 33928 bytes 16 active, 1008 inactive, 12320 added, 6160 added to flow 0 alloc failures, 0 force free 1 chunk, 1 chunk added
SrcAddress InpIf DstAddress OutIf Prot SrcPrt DstPrt Packets 2001:DB...06::201 Gi0/0 2001:DB...28::20 Local 0x06 0x6851 0x1466 6461 2001:DB...6A:5BA6 Gi0/0 2001:DB...28::21 Gi0/1 0x3A 0x0000 0x8000 1191 2001:DB...6A:5BA6 Gi0/0 2001:DB...134::3 Gi0/1 0x3A 0x0000 0x8000 1191 2001:DB...6A:5BA6 Gi0/0 2001:DB...128::4 Gi0/1 0x3A 0x0000 0x8000 1192 2001:DB...6A:5BA6 Gi0/0 2001:DB...128::2 Gi0/1 0x06 0x6852 0x1466 2787 2001:DB...06::202 Gi0/0 2001:DB...128::3 Gi0/1 0x06 0x6853 0x1466 3401 2001:DB...06::201 Gi0/0 2001:DB...128::4 Gi0/1 0x11 0x1634 0x13C4 1292 2001:DB...6A:5BA6 Gi0/0 2001:DB...128::3 Gi0/1 0x3A 0x0000 0x8000 1155 2001:DB...6A:5BA6 Gi0/0 2001:DB...146::3 Gi0/1 0x06 0x6854 0x1466 1492 2001:DB...6A:5BA6 Gi0/0 2001:DB...144::4 Gi0/1 0x3A 0x0000 0x8000 1193
To permit display of the full 128-bit IPv6 address, use the terminal width 132 exec mode command.
In the preceding example, there are multiple IPv6 flows for XMPP on TCP port 5222 (hex value 1466).
As shown in the following example, to view only the XMPP packets on TCP port 5222 (hex value 1466), use the show ipv6 flow cache | include SrcIf|_06_.*1466 command to display the related Cisco NetFlow records:
TCP Flows
router#show ipv6 flow cache | include SrcIf|_06_.*1466 SrcAddress InpIf DstAddress OutIf Prot SrcPrt DstPrt Packets 2001:DB...6A:5BA6 Gi0/0 2001:DB...128::2 Gi0/1 0x06 0x160A 0x1466 1597 router#
Identification: IPv4 Traffic Flow Identification Using Cisco Flexible NetFlow
Introduced in Cisco IOS Software Releases 12.2(31)SB2 and 12.4(9)T, Cisco IOS Flexible NetFlow improves original Cisco NetFlow by adding the capability to customize the traffic analysis parameters for the administrator's specific requirements. Original Cisco NetFlow uses a fixed seven tuples of IP information to identify a flow, whereas Cisco IOS Flexible NetFlow allows the flow to be user defined. It facilitates the creation of more complex configurations for traffic analysis and data export by using reusable configuration components.
The following example output is from a Cisco IOS device that is running a version of Cisco IOS Software in the 15.1T train. Although the syntax will be almost identical for the 12.4T and 15.0 trains, it may vary slightly depending on the actual Cisco IOS release being used. In the following configuration, Cisco IOS Flexible NetFlow will collect information on interface GigabitEthernet0/0 for incoming IPv4 flows based on source IPv4 address, as defined by the match ipv4 source address key field statement. Cisco IOS Flexible NetFlow will also include nonkey field information about source and destination IPv4 addresses, protocol, ports (if present), ingress and egress interfaces, and packets per flow.
! !-- Configure key and nonkey fields !-- in the user-defined flow record ! flow record FLOW-RECORD-ipv4 match ipv4 source address collect ipv4 protocol collect ipv4 destination address collect transport source-port collect transport destination-port collect interface input collect interface output collect counter packets ! !-- Configure the flow monitor to !-- reference the user-defined flow !-- record ! flow monitor FLOW-MONITOR-ipv4 record FLOW-RECORD-ipv4 ! !-- Apply the flow monitor to the interface !-- in the ingress direction ! interface GigabitEthernet0/0 ip flow monitor FLOW-MONITOR-ipv4 input
The Cisco IOS Flexible NetFlow flow output is as follows:
router#show flow monitor FLOW-MONITOR-ipv4 cache format table Cache type: Normal Cache size: 4096 Current entries: 6 High Watermark: 1 Flows added: 9181 Flows aged: 9175 - Active timeout ( 1800 secs) 9000 - Inactive timeout ( 15 secs) 175 - Event aged 0 - Watermark aged 0 - Emergency aged 0 IPV4 SRC ADDR ipv4 dst addr trns src port trns dst port intf input intf output pkts ip prot ============== ============== ============= ============= ========== =========== ===== ======= 192.168.10.201 192.168.60.102 1456 53 Gi0/0 Gi0/1 1128 17 192.168.11.54 192.168.60.158 123 123 Gi0/0 Gi0/1 2212 17 192.168.150.60 10.89.16.226 2567 443 Gi0/0 Gi0/1 13 6 192.168.13.97 192.168.60.28 3451 5222 Gi0/0 Gi0/1 91 6 192.168.10.17 192.168.60.97 3452 5222 Gi0/0 Gi0/1 146 6 10.88.226.1 192.168.202.22 2678 443 Gi0/0 Gi0/1 10567 6 10.89.16.226 192.168.150.60 3562 80 Gi0/0 Gi0/1 30012 6To only view the XMPP packets on TCP port 5222, use the show flow monitor FLOW-MONITOR-ipv4 cache format table | include IPV4 DST ADDR |_5222_.*_6_ command to display the related NetFlow records.
For more information about Cisco IOS Flexible NetFlow, refer to Flexible Netflow Configuration Guide, Cisco IOS Release 15.1M&T and Cisco IOS Flexible NetFlow Configuration Guide, Release 12.4T.
Identification: IPv6 Traffic Flow Identification Using Cisco IOS Flexible NetFlow
The following example output is from a Cisco IOS device that is running a version of Cisco IOS Software in the 15.1T train. Although the syntax will be almost identical for the 12.4T and 15.0 trains, it may vary slightly depending on the actual Cisco IOS release being used. In the following configuration, Cisco IOS Flexible NetFlow will collect information on interface GigabitEthernet0/0 for incoming IPv6 flows based on the source IPv6 address, as defined by the match ipv6 source address key field statement. Cisco IOS Flexible NetFlow will also include nonkey field information about source and destination IPv6 addresses, protocol, ports (if present), ingress and egress interfaces, and packets per flow.! !-- Configure key and nonkey fields !-- in the user-defined flow record ! flow record FLOW-RECORD-ipv6 match ipv6 source address collect ipv6 protocol collect ipv6 destination address collect transport source-port collect transport destination-port collect interface input collect interface output collect counter packets ! !-- Configure the flow monitor to !-- reference the user-defined flow !-- record ! flow monitor FLOW-MONITOR-ipv6 record FLOW-RECORD-ipv6 ! !-- Apply the flow monitor to the interface !-- in the ingress direction ! interface GigabitEthernet0/0 ipv6 flow monitor FLOW-MONITOR-ipv6 input
The Cisco IOS Flexible NetFlow flow output is as follows:
router#show flow monitor FLOW-MONITOR-ipv6 cache format table Cache type: Normal Cache size: 4096 Current entries: 6 High Watermark: 2 Flows added: 539 Flows aged: 532 - Active timeout ( 1800 secs) 350 - Inactive timeout ( 15 secs) 182 - Event aged 0 - Watermark aged 0 - Emergency aged 0 IPV6 SRC ADDR ipv6 dst addr trns src port trns dst port intf input intf output pkts ip prot ================= ================ ============= ============= ========== =========== ==== ======= 2001:DB...06::201 2001:DB...28::20 123 123 Gi0/0 Gi0/0 17 17 2001:DB...06::201 2001:DB...28::20 4856 5222 Gi0/0 Gi0/0 98 6 2001:DB...06::201 2001:DB...28::20 4855 5222 Gi0/0 Gi0/0 87 6 2001:DB...06::201 2001:DB...28::20 2856 5060 Gi0/0 Gi0/0 486 17 2001:DB...06::201 2001:DB...28::20 3012 53 Gi0/0 Gi0/0 1016 17 2001:DB...06::201 2001:DB...28::20 2477 53 Gi0/0 Gi0/0 1563 17To permit display of the full 128-bit IPv6 address, use the terminal width 132 exec mode command.
To view only the XMPP packets on TCP port 5222, use the show flow monitor FLOW-MONITOR-ipv6 cache format table | include IPV6 DST ADDR|_5222_.*_6_ command to display the related Cisco IOS Flexible NetFlow records.
Cisco ASA, Cisco ASASM, and Cisco FWSM Firewalls
Mitigation: Transit Access Control Lists
To protect the network from traffic that enters the network at ingress access points, which may include Internet connection points, partner and supplier connection points, or VPN connection points, administrators are advised to deploy tACLs to perform policy enforcement. Administrators can construct a tACL by explicitly permitting only authorized traffic to enter the network at ingress access points or permitting authorized traffic to transit the network in accordance with existing security policies and configurations. A tACL workaround cannot provide complete protection against this vulnerability when the attack originates from a trusted source address.
The tACL policy denies unauthorized XMPP IPv4 and IPv6 packets on TCP port 5222 that are sent to affected devices. In the following example, 192.168.60.0/24 and 2001:DB8:1:60::/64 represent the IP address space that is used by the affected devices, and the hosts at 192.168.100.1 and 2001:DB8::100:1 are considered trusted sources that require access to the affected devices. Care should be taken to allow required traffic for routing and administrative access prior to denying all unauthorized traffic.
Additional information about tACLs is in Transit Access Control Lists: Filtering at Your Edge.
! !-- Include explicit permit statements for trusted sources !-- that require access on the vulnerable TCP port ! access-list tACL-Policy extended permit tcp host 192.168.100.1 192.168.60.0 255.255.255.0 eq 5222 ! !-- The following vulnerability-specific access control entry !-- (ACE) can aid in identification of attacks ! access-list tACL-Policy extended deny tcp any 192.168.60.0 255.255.255.0 eq 5222 ! !-- Permit or deny all other Layer 3 and Layer 4 traffic in accordance !-- with existing security policies and configurations ! !-- Explicit deny for all other IP traffic ! access-list tACL-Policy extended deny ip any any ! !-- Create the corresponding IPv6 tACL ! !-- Include explicit permit statements for trusted sources !-- that require access on the vulnerable TCP port ! ipv6 access-list IPv6-tACL-Policy permit tcp host 2001:DB8::100:1 2001:db8:1:60::/64 eq 5222 ! !-- The following vulnerability-specific access control entry !-- (ACE) can aid in identification of attacks ! ipv6 access-list IPv6-tACL-Policy deny tcp any 2001:db8:1:60::/64 eq 5222 ! !-- Permit or deny all other Layer 3 and Layer 4 traffic in accordance !-- with existing security policies and configurations ! !-- Explicit deny for all other IP traffic ! ipv6 access-list IPv6-tACL-Policy deny ip any any ! !-- Apply tACLs to interfaces in the ingress direction ! access-group tACL-Policy in interface outside access-group IPv6-tACL-Policy in interface outside
Identification: Transit Access Control Lists
After the tACL has been applied to an interface, administrators can use the show access-list command to identify the number of XMPP IPv4 and IPv6 packets on TCP port 5222 that have been filtered. Administrators are advised to investigate filtered packets to determine whether they are attempts to exploit this vulnerability. Example output for show access-list tACL-Policy and show access-list IPv6-tACL-Policy follows:
firewall#show access-list tACL-Policy access-list tACL-Policy; 3 elements; name hash: 0x383dd03d access-list tACL-Policy line 1 extended permit tcp host 192.168.100.1 192.168.60.0 255.255.255.0 eq 5222 (hitcnt=31) access-list tACL-Policy line 2 extended deny tcp any 192.168.60.0 255.255.255.0 eq 5222 (hitcnt=8) access-list tACL-Policy line 3 extended deny ip any any (hitcnt=8)In the preceding example, access list tACL-Policy has dropped 8 XMPP packets on TCP port 5222 received from an untrusted host or network. In addition, syslog message 106023 can provide valuable information, which includes the source and destination IP address, the source and destination port numbers, and the IP protocol for the denied packet.
firewall#show access-list IPv6-tACL-Policy ipv6 access-list IPv6-tACL-Policy; 3 elements; name hash: 0x564a2629 ipv6 access-list IPv6-tACL-Policy line 1 permit tcp host 2001:db8:1:100::1 2001:db8:1:60::/64 eq 5222 (hitcnt=30) ipv6 access-list IPv6-tACL-Policy line 2 deny tcp any 2001:db8:1:60::/64 eq 5222 (hitcnt=29) ipv6 access-list IPv6-tACL-Policy line 3 deny ip any any (hitcnt=927)In the preceding example, access list IPv6-tACL-Policy has dropped 29 XMPP packets on TCP port 5222 received from an untrusted host or network. In addition, syslog message 106023 can provide valuable information, which includes the source and destination IP address, the source and destination port numbers, and the IP protocol for the denied packet.
Identification: Firewall Access List Syslog Messages
Firewall syslog message 106023 will be generated for packets denied by an access control entry (ACE) that does not have the log keyword present. Additional information about this syslog message is in Cisco ASA 5500 Series System Log Message, 8.2 - 106023.
Information about configuring syslog for the Cisco ASA 5500 Series Adaptive Security Appliance is in Monitoring - Configuring Logging. Information about configuring syslog on the Cisco Catalyst 6500 Series ASA Services Module is in Configuring Logging. Information about configuring syslog on the FWSM for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers is in Monitoring the Firewall Services Module.
In the following example, the show logging | grep regex command extracts syslog messages from the logging buffer on the firewall. These messages provide additional information about denied packets that could indicate potential attempts to exploit the vulnerability that is described in this document. It is possible to use different regular expressions with the grep keyword to search for specific data in the logged messages.
Additional information about regular expression syntax is in Creating a Regular Expression.
firewall#show logging | grep 106023 Sep 12 2012 00:15:13: %ASA-4-106023: Deny tcp src outside:192.0.2.18/6894 dst inside:192.168.60.191/5222 by access-group "tACL-Policy" Sep 12 2012 00:15:13: %ASA-4-106023: Deny tcp src outside:192.0.2.200/6895 dst inside:192.168.60.33/5222 by access-group "tACL-Policy" Sep 12 2012 00:15:13: %ASA-4-106023: Deny tcp src outside:192.0.2.99/6896 dst inside:192.168.60.240/5222 by access-group "tACL-Policy" firewall#In the preceding example, the messages logged for the tACL tACL-Policy show XMPP packets for TCP port 5222 sent to the address block assigned to affected devices.
Additional information about syslog messages for Cisco ASA Series Adaptive Security Appliances is in Cisco ASA 5500 Series System Log Messages, 8.2. Additional information about syslog messages for Cisco Catalyst 6500 Series ASA Services Module is in the Analyzing Syslog Messages section of the Cisco ASASM CLI Configuration Guide. Additional information about syslog messages for the Cisco FWSM is in Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Logging System Log Messages.
For additional information about investigating incidents using syslog events, reference the Identifying Incidents Using Firewall and IOS Router Syslog Events Cisco Security Intelligence Operations white paper.
Cisco Security Manager
Identification: Cisco Security Manager
Cisco Security Manager, Event Viewer
Beginning in software version 4.0, Cisco Security Manager can collect syslogs from Cisco firewalls and Cisco IPS devices and provides the Event Viewer, which can query for events that are related to the vulnerability that is described in this document.
Using the following filters in the Firewall Denied Events predefined view in the Event Viewer provides all captured Cisco firewall access list deny syslog messages that could indicate potential attempts to exploit the vulnerability that is described in this document.
- Use the Destination event filter to filter network objects that contain the IP address space that is used by the affected devices (for example, IPv4 address range 192.168.60.0/24 and IPv6 address range 2001:DB8:1:60::/64)
- Use the Destination Service event filter to filter objects that contain TCP port 5222
An Event Type ID filter can be used with the Firewall Denied Events predefined view in the Event Viewer to filter the syslog IDs shown in the following list to provide all captured Cisco firewall deny syslog messages that could indicate potential attempts to exploit the vulnerability that is described in this document:
- ASA-4-106023 (ACL deny)
For more information about Cisco Security Manager Events, refer to the Filtering and Querying Events section of the Cisco Security Manager User Guide.
Identification: Event Management System Partner Events
Cisco works with industry-leading Security Information and Event Management (SIEM) companies through the Cisco Developer Network. This partnership helps Cisco deliver validated and tested SIEM systems that address business concerns such as long-term log archiving and forensics, heterogeneous event correlation, and advanced compliance reporting. Security Information and Event Management partner products can be leveraged to collect events from Cisco devices and then query the collected events for the incidents created by a Cisco IPS signature or deny syslog messages from firewalls that could indicate potential attempts to exploit the vulnerability that is described in this document. The queries can be made by Sig ID and Syslog ID as shown in the following list:
- ASA-4-106023 (ACL deny)
For more information about SIEM partners, refer to the Security Management System website.
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THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
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Show LessVersion Description Section Date 2 This document has been updated to improve the formatting of NetFlow tables. 2012-September-12 21:51 GMT 1 Cisco Applied Mitigation Bulletin initial public release 2012-September-12 16:01 GMT
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Complete information on reporting security vulnerabilities in Cisco products, obtaining assistance with security incidents, and registering to receive security information from Cisco, is available on Cisco's worldwide website at https://sec.cloudapps.cisco.com/security/center/resources/security_vulnerability_policy.html. This includes instructions for press inquiries regarding Cisco security notices. All Cisco security advisories are available at http://www.cisco.com/go/psirt.
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The security vulnerability applies to the following combinations of products.
Primary Products Cisco Cisco Unified Presence Server 1.0 (.1, .2, .3) | 6.0 (Base, .1, .2, .3, .4, .5, .6, .7) | 7.0 (Base, .1, .2, .3, .4, .5, .6, .7, .8) | 8.0 (.1, .2) | 8.5 (.1, .2, .3, .4, .5) Cisco Jabber Extensible Communications Platform (Jabber XCP) 4.0 (Base) | 5.2 (Base)
Associated Products
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THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE ALERTS AT ANY TIME.
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