Big debate over small packets
Attacking the internet through ICMP vulns
Fernando Gont is nothing if not tenacious.
Earlier this year, the Argentinian researcher highlighted several attacks that could disrupt network connections using the Internet control message protocol, or ICMP, and proposed four changes to the structure and handling of network-data packets that would essentially eliminate the risk.
However, rather than open up a discussion on the flaws and their fixes, Gont's disclosure marked the start of a months-long debate over whether the vulnerabilities - the general details of which have been known for some time - are serious enough to require fixing. While many researchers have lauded his research, others in the security community have criticized the work on public mailing lists. The few companies that Gont has contacted have not generally cooperated, and very few makers of operating systems and network software have implemented his fixes.
Yet, the researcher is at it again. This week, Gont updated his proposal to the Internet Engineering Task Force (IETF), the body that handles technical standards for the Internet, to add more information sought by some researchers.
"Some people say 'this is old stuff,'" said Gont, currently on staff at the Universidad Tecnologica Nacional (National University of Technology) in Argentina. "But they miss a very important point: While these attacks have been known to many people for many years, there have never been proposals on how to deal with them."
The flaws are essentially issues caused by the lack of a requirement in the Internet standards to check ICMP packets for specific, problematic data. By sending enough malformed ICMP packets at a vulnerable server or network router, an attack could shutdown a connection, cause a degradation in network bandwidth, or cause the host to burn processor cycles, Gont said.
The issues affect a large number of networking products and operating systems. While a vulnerability note released by the United States' Computer Emergency Readiness Team (US-CERT) in April indicates that the lion's share of vendors have not declared if their products are vulnerable, major vendors - such as Cisco Systems, Juniper Networks, Microsoft and Sun Microsystems - have confirmed the security issue affects their systems, according to the vulnerability note.
An analysis of the vulnerabilities by the National Infrastructure Security Co-ordination Centre, United Kingdom's version of US-CERT, contains more information about vulnerable systems.
Cisco addressed the issues in an update to a wide variety of products in April, following Gont's first presentation of the issues at CanSecWest in Vancouver. Cisco confirmed all three attacks but did not comment on their severity.
"We take all research like this very seriously," said Cisco spokesman John Noh.
To Gont, the problems are serious. To others, the potential attacks are too complicated and gain the attacker too little to be much of a threat.
"To some people, any possible avenue of attack is a serious issue," said Mark Allman, co-chair of the TCP Maintenance and Minor Extensions working group at the IETF. "Sometimes we need the paranoid folk's beating of the drum, but often times, these sorts of folks work in the minutia."
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