Imagine being able to disconnect or redirect Internet traffic destined for some of the world’s biggest companies — just by spoofing an email. This is the nature of a threat vector recently removed by a Fortune 500 firm that operates one of the largest Internet backbones. //

For a long time, any changes to an organization’s routing information with an IRR could be processed via email as long as one of the following authentication methods was successfully used:

• A password is added to the text of an email to the IRR
• The requestor signs the email containing the update with an encryption key
• The requestor sends the record changes in an email to the IRR, and the authentication is based solely on the “From:” header of the email.

Of these, MAIL-FROM has long been considered insecure, for the simple reason that it’s not difficult to spoof the return address of an email. And virtually all IRRs have disallowed its use since at least 2012, said Adam Korab, a network engineer and security researcher based in Houston.

All except Level 3 Communications, a major Internet backbone provider acquired by Lumen/CenturyLink.

“LEVEL 3 is the last IRR operator which allows the use of this method, although they have discouraged its use since at least 2012,” Korab told KrebsOnSecurity. “Other IRR operators have fully deprecated MAIL-FROM.”

Importantly, the name and email address of each Autonomous System’s official contact for making updates with the IRRs is public information. //

Lumen told KrebsOnSecurity that it continued offering MAIL-FROM: authentication because many of its customers still relied on it due to legacy systems. Nevertheless, after receiving Korab’s report the company decided the wisest course of action was to disable MAIL-FROM: authentication altogether. //

While it’s nice that Lumen is no longer the weakest link in the IRR chain, the remaining authentication mechanisms aren’t great. Claffy said after years of debate over approaches to improving routing security, the operator community deployed an alternative known as the Resource Public Key Infrastructure (RPKI).

“The RPKI includes cryptographic attestation of records, including expiration dates, with each Regional Internet Registry (RIR) operating as a ‘root’ of trust,” wrote Claffy and two other UC San Diego researchers in a paper that is still undergoing peer review. “Similar to the IRR, operators can use the RPKI to discard routing messages that do not pass origin validation checks.”

However, the additional integrity RPKI brings also comes with a fair amount of added complexity and cost, the researchers found. //

Dave
November 26, 2021

The problem with RPKI as a security mechanism is that they handed the problem of securing BGP over to a bunch of X.509 fanboys, and so the result was something that looked suspiciously like X.509…. no, I stand corrected, it is X.509. It’s an attempt to use an X.509 certificate in a way that was never designed for, combined with the mass of other problems that make X.509 such a joy to use.