Cisco patches bug that crashed 1 percent of Internet

A Duke University experiment inadvertently uncovered a bug in Cisco IOS XR

Cisco has fixed a bug in its IOS (Internetwork Operating System) router software that contributed to a brief Internet blackout last week, thought to have affected about 1 percent of the Internet.

The bug was discovered last Friday when the RIPE NCC (Reseaux IP Europeens Network Coordination Centre) and researchers at Duke University started distributing experimental BGP (Border Gateway Protocol) data via RIPE NCC's systems. A large number of routers on the Internet became unreachable within minutes and the experiment was quickly stopped.

The Border Gateway Protocol is used by routers to find the best ways to send traffic to each other on the Internet. Because it is very easy for bad BGP data to spread quickly, security experts have warned that it could someday be misused to seriously disrupt the Internet.

It turned out that routers that were running Cisco's IOS XR operating system took the experimental data -- which was much larger than typical BGP routing information -- corrupted it, and then passed that corrupted information on to other routers. Many of the routers that received this information simply closed connections with the Cisco routers that sent the buggy data, causing part of the Internet to become inaccessible.

In a security advisory released just hours after the incident, Cisco confirmed that Friday's incident disclosed the bug. "An advertisement of an unrecognized but valid BGP attribute resulted in resetting of several BGP neighbors on 27 August 2010. This advertisement was not malicious but inadvertently triggered this vulnerability," Cisco said in its advisory.

Cisco's IOS XR operating system is built for its carrier-grade CRS-1 routers, used by large telecommunications companies.

Reached via e-mail Friday, Duke University assistant professor Xiaowei Yang declined to explain the point of her experiment, but she said that all of the data that her team sent was "100 percent standard compliant."

The experiment made it difficult to reach some networks in more than 60 countries, according to Renesys General Manager Earl Zmijewski, who blogged about the issue on Friday. More than 3,500 "prefixes," or blocks of Internet Protocol address space, were affected, he said. There are just over 333,000 such prefixes on the Internet, according to the website Cidr-report.org.

Friday's disruption lasted less than half an hour.

In an interview Monday, Zmijewski said that while Cisco's buggy software caused the problems, the Duke team running the experiment should have been more careful. "The days of academics playing with a live network are kind of gone now," he said. "I think it would be foolhardy to try something like this in the future. ... I'm amazed that this happened in the first place."

RIPE NCC representatives did not respond to messages seeking comment, but in a note posted Sunday, the organization said the experiment was intended "to further global understanding of specific aspects of Internet routing behaviour."

RIPE NCC is going to be stricter about the way it runs such experiments and will give Internet operators advance warning in the future, the group said.

Cisco declined to comment on the matter beyond what it has outlined in its security advisory.

Robert McMillan covers computer security and general technology breaking news for The IDG News Service. Follow Robert on Twitter at @bobmcmillan. Robert's e-mail address is robert_mcmillan@idg.com

Join the PC World newsletter!

Error: Please check your email address.

Tags patchesCisco SystemsNetworkingsecurityinternet

Our Back to Business guide highlights the best products for you to boost your productivity at home, on the road, at the office, or in the classroom.

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Robert McMillan

IDG News Service
Show Comments

Essentials

Microsoft L5V-00027 Sculpt Ergonomic Keyboard Desktop

Learn more >

Lexar® JumpDrive® S57 USB 3.0 flash drive

Learn more >

Mobile

Lexar® JumpDrive® S45 USB 3.0 flash drive 

Learn more >

Exec

HD Pan/Tilt Wi-Fi Camera with Night Vision NC450

Learn more >

Lexar® Professional 1800x microSDHC™/microSDXC™ UHS-II cards 

Learn more >

Lexar® JumpDrive® C20c USB Type-C flash drive 

Learn more >

Audio-Technica ATH-ANC70 Noise Cancelling Headphones

Learn more >

Budget

Back To Business Guide

Click for more ›

Most Popular Reviews

Latest News Articles

Resources

PCW Evaluation Team

Michael Hargreaves

Windows 10 for Business / Dell XPS 13

I’d happily recommend this touchscreen laptop and Windows 10 as a great way to get serious work done at a desk or on the road.

Aysha Strobbe

Windows 10 / HP Spectre x360

Ultimately, I think the Windows 10 environment is excellent for me as it caters for so many different uses. The inclusion of the Xbox app is also great for when you need some downtime too!

Mark Escubio

Windows 10 / Lenovo Yoga 910

For me, the Xbox Play Anywhere is a great new feature as it allows you to play your current Xbox games with higher resolutions and better graphics without forking out extra cash for another copy. Although available titles are still scarce, but I’m sure it will grow in time.

Kathy Cassidy

STYLISTIC Q702

First impression on unpacking the Q702 test unit was the solid feel and clean, minimalist styling.

Anthony Grifoni

STYLISTIC Q572

For work use, Microsoft Word and Excel programs pre-installed on the device are adequate for preparing short documents.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?