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IPS Tech Talk – Global Correlation 2010 November 18

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Thanks for joining!We will begin in just a few minutes as more people come on line. This event will be recorded.

ips tech talk global correlation 2010 november 18

IPS Tech Talk – Global Correlation2010 November 18

Robert Albach, James Kasper, Chad Rhyner

tech talk mechanics how these events will operate
Tech Talk MechanicsHow these events will operate
  • With many people on-line we will mute all but the presenters
  • We will try to answer questions at the end
    • Please use the “Question and Answer” feature for questions
    • If we don’t get to your question, we will try to answer them off-line
  • The presentation and recording will be placed on the Community support site:

global correlation simple view
Global Correlation – Simple View




Cisco IPS

cisco global correlation sensorbase world s largest traffic monitoring network
Cisco Global CorrelationSensorBase: World’s Largest Traffic Monitoring Network

Cisco SensorBase

  • 700,000+ sensors deployed globally
  • 8 of the top 10 global ISPs
  • Over 500GB of data per day
  • 152 third party feeds
  • Over 30% of the world’s email traffic
cisco global correlation sensor contribution
Cisco Global CorrelationSensor Contribution

Email Security


Web Security


Identifying a global botnet requires complete visibility across all threat vectors


IPS 7.x Global Correlation - Support

  • Released Spring 2009 as version 7.0(1)
  • Which Devices Can Use Global Correlation:
  • 4240, 4255, 4260, 4270 IPS appliances
  • IDSM2 Cisco Catalyst blades
  • IPS-AIM and IPS-NMEISR modules
  • AIP modules for ASA appliances
  • Which Devices CAN NOT Use Global Correlation:
  • Cisco IOS IPS
  • ASA 5505 with AIP-SSC5 card
  • IPS 4215

IPS 7.0 Global Correlation - Activities

  • Global Correlation Inspection (GC)

Use “Reputation” knowledge of Attackers to influence Alarm handling and Denies when there are “Bad Score” attackers seen on the sensor.

  • Reputation Filter (RF)

Apply automatic deny of packets from known malicious sites.

  • Network Participation (NP)

Sensor sends sampled and condensed alarm data and statistics to central “IBNP server” for global analysis.

quick poll
Quick Poll
  • Global Correlation and You…

Global Correlation in the IPS

  • Fully automatic handling of sensor’s uploads and downloads of this Global Correlation and participation data.
  • Apply intelligent handling to alarms
  • Improve efficacy - the effectiveness of our defensive action handling.
  • Improve protection against known malicious sites (by IP address range) with a fully automatic ingress filter.
  • Share telemetry data with Cisco back-endprocessing to improve visibility of alarms and sensor actions on a global scale. This feeds various analysis tools.

Configuration Options

  • Service host / network-settings

DNS-server (primary, secondary, tertiary) OR

HTTP-Proxy (address and port)

  • Service global-correlation

Network Participation

On / Off

Participation Mode (Partial or Full)

Global Correlation Inspection

On / Off

Influence (parameter to set how aggressive the function behaves)

Reputation Filter

On / Off

Test Global Correlation (audit mode)

On / Off


Automatic GC updates

  • Fully automatic beyond configuration
  • Cisco distributes the update files via Akamai caches for load balancing, redundancy, and locality.
  • Update interval can happen every 5 minutes, as needed.
  • Sensor first gets a “FULL” update of components, then applies “INCREMENTAL” updates periodically (as new updates are available)
    • Initial Full updates range upwards from 2G in size
    • Incremental are typically 100K in size
  • Each data set has a serial #, displayed in the GC stats. This serial # represents the latest dataset loaded by the sensor. This is informational and does not require any user interaction.
global correlation reputation updates
Global Correlation Reputation Updates

Initiate request to update reputation data through HTTPS request

Sensor gets back a manifest containing the DNS name of a server to get the data from

DNS request returns the nearest Akamai server

Initiate actual data download using HTTP from the Akamai server





2 URL list of local Akamai servers is returned


3 ‘Akamaized’ DNS request for nearest server


1 IPS initiates request to update reputation data

4 IPS initiates actual data download over HTTP



demosensor1# show statistics global

. . . .

Update Server =

Update Server Address =

Current Versions:

config = 1236210407

drop = 1245425355

ip = 1245424447

rule = 1245348807

Reputation data comes in the form of multiple files (config, drop, ip, rule) that get downloaded as needed during updates


Network Participation

  • Per Alarm shows:

The partial mode telemetry data includes:


Attacker Address and Port

Signature Version

GC Reputation Score

Risk Rating fields

  • AnalysisEngine GC Stats

Alerts Hits/Miss

GC Reputation actions

Packet Denies counters

  • FULL mode adds: Victim IP and Port

Reputation Filtering: Deny Filter Processor

  • Deny Attacker addresses registered here.
  • GlobalCorrelationReputationFilter registered here.
  • This is an INGRESS filter, and will drop packets matching deny attacker or RF.
  • Deny Attacker is most aggressive action.
  • Deny Attacker can come from SigEvent action, manual user command, and GC alarm feature.
  • Deny Attacker modes:
    • Axxx: deny-attacker
    • AxBx: deny-attacker-victim-pair
    • Axxb: deny-attacker-service-pair
how is risk rating determined
How is Risk Rating Determined?
  • Risk Rating has multiple contributing inputs.
    • Attack Severity Rating – derived from other inputs (more to come)
    • Target Value Rating – configurable by user
    • Signature Fidelity Rating – pre-set by Cisco for each signature
    • Attack Relevance Rating – derived from other inputs (more to come)
    • Promiscuous Delta – derived value – impacted by IDS mode
    • Watch List Rating – derived from internal list data (more to come)
    • *Global Correlation – (7.0 and later)

+ Risk Delta

global correlation and risk rating
Global Correlation and Risk Rating
  • For 7.0+ releases you have access to Cisco Global Correlation Reputation data
  • There are three modes that let you determine how aggressively the sensor uses global correlation information to initiate deny actions:
    • Permissive: Modifies standard Risk Rating w Risk Delta (below).
    • Standard: Permissive but uses lower internal overide thresholds.
    • Deny Packet – 86 Deny Attacker - 100
    • Aggressive: Standard but uses even lower override thresholds.
    • Deny Packet – 83 Deny Attacker - 95

+ Risk Delta


Some Debugging Information

  • local network devices

May have to open up port 443 or proxy port at gateway

  • Statistics of interest

Show stat analysis-engine

Show stat global-correlation

  • Show version displays license information.
  • GC license feature requires proper time/date setting.
  • ReputationFilter drops are seen in analysis-engine statistics.
what might be some limitations
What might be some limitations?
  • IPS location may make a difference.
  • Example:
    • If inspecting only internal traffic then external reputation data may not have much meaning (Global Correlation) less impact but my internal watch list info is a better fit.
global correlation summary
Global Correlation Summary
  • Global Correlation helps you to:
    • Reduces traffic with Reputation Filters prior to deep inspection
    • Influences actions taken by the IPS by altering Risk Ratings
    • Global Correlation is easy:
      • Downloads are automated and simple to set up
    • Global Correlation is made better by you!
      • Your participation improves yours and others identification of attackers and bad sites
quick poll1
Quick Poll
  • Global Correlation and You…
before the q a session
Before the Q&A Session
  • Thanks for attending.
  • Let us know:
    • Was this session worth while to you?
    • What future topics would you like to see?
    • How might we improve these events?
  • Send an email to:
    • Robert Albach