When Technology Falters: The CareGroup Network Outage John D. Halamka MD CIO, CareGroup CIO, Harvard Medical School

Agenda  In depth overview of the Network Outage  Key Lessons  The Sequel – SQL Slammer  Questions and Answers

CareGroup Network as Built

Timeline  November 13, :45pm –Napster-like internal attack –Change begins, redundant links cut –Callisma and Cisco on site  November 14, 2002 –Spanning tree issues –WAN issues –CAP declared at 4:00pm

Core Switch Utilization

Timeline  November 15, 2002 –PACS Rebuild –Research/Cardiology rebuild –Reboot of core and distribution layer  November 16, 2002 –VLAN mismatch –Redundant Core built as contingency

Core Switch Utilization

Root Cause Analysis  CareGroup Network grew organically by Merger and Acquisition into a massive bridged switched network which was not within Spanning Tree spec  Equipment was not life cycle managed  Router/switch configuration was not in accordance with best practices i.e. multicast dense mode

Spanning Tree Problems  When TAC was first able to access and assess the network, we found the Layer 2 structure of the network to be unstable and out of specification with 802.1d standards. The management vlan (vlan 1) had in some locations 10 Layer 2 hops from root.  The conservative default values for the Spanning Tree Protocol (STP) impose a maximum network diameter of seven. This means that two distinct bridges in the network should not be more than seven hops away from one to the other.

Key Lessons  Partner with your network vendor –Encourage external audits of your network –Engage advanced engineering services –Avoid senior management blind spots

Key Lessons  Avoid flat topology bridged switched networks. Best Practice CareGroup Network One VLAN per Subnet per VLANs span many physical switches physical switches Limited or no bridging Extensive use of bridging Layer 2 switching limited to Layer 2 switching access layerextended across core

Key Lessons  Re-evaluate the enterprise architecture of your network –Routed core –Switched distribution and access layers –Robust Firewall

Key Lessons  Life Cycle Manage your network –Eliminate Legacy Protocols –Recognize the value of new feature sets –Hardware must keep up with the demands of a changing organization – video over IP, IP telephony, bioinformatics, image management

Key Lessons  Implement appropriate monitoring and diagnostic tools to maintain the health and hygiene of your network –Concord –NATKit –CiscoWorks –OpenView

Key Lessons  Have a robust downtime plan –Out of band diagnostics –Dial up modems and computers in key clinical areas –Overview of CareGroup Disaster Recovery plan

Service Objectives

Protection Features

Protection features

Protection Techniques Cost versus Benefit

Protection Techniques by Vulnerability

Key Lessons  Implement Strict Change Control –Standards, configurations, devices, protocols, links, processes, procedures, or services –Prior review and approval of all network infrastructure changes –Multi-discipline membership –Changes classed as substantial, moderate, or minimal impact

Key Lessons  Implement Strict Change Control (cont) –Substantial changes require Cisco AES review –Changes scheduled 2am – 5am weekends –Changes require baseline, testing, and recovery plans –As-Built documentation to include overall, physical and logical diagrams –NCCB recommends expense allocation

The Sequel – SQL Slammer  Released at 12:30am on January 25  Infected East Coast at 12:40am  Microsoft SQLServer 2000 was patched, however Microsoft did not issue any patches or security warnings on Microsoft Data Engine 2000 (MSDE), which is included with numerous desktop products

Spread of the Worm

Exact effect on CareGroup  MSDE and non-IS maintained databases infected  Network saturated by worm activity  Shut off links to Research areas  Blocked all traffic from the public internet  Network traffic levels returned to normal

Cleanup  Restart of servers and desktops that were disrupted by the outage  Once all areas research areas had cleaned desktops, we restored port 1433 connectivity

Further Lessons learned  VPN as a security risk  Implement a scanning program to analyze research desktop and server vulnerabilities  Ensure you have modern network equipment that afford you the tools to control intra-VLAN traffic

Conclusions  Lifecycle manage your network just as you would your desktop  Ensure senior management understands the value of the network as a strategic asset  Build great downtime procedures including out of band connectivity just in case the technology falters