tssci security

Protecting the global Internet routing infrastructure

Arbor Networks has a blog post up today about Using RPKI to Construct Validated IRR Data. Resource PKI (RPKI) is an extension to X.509 to allow for IP address (prefix) and AS identifiers (autonomous system numbers -- the organization-based assigned number used by the Border Gateway Protocol to get you or your ISP "online").

My first introduction to hijacking traffic at a global level was in 1997. A certain ISP that I knew would typically test their attack theories and concepts live by re-routing, redirecting, and outright stealing traffic using BGP-4. It was often done to spammers, typically those already in a customer relationship with the provider.

By using a TCP/IP routing concept known as a "more-specific route", or MSR as I like to refer to it -- a route injected into the RIB (routing information base, or "routing table" as most people call it) that has a shorter-prefix (a /24 instead of a /23) will be selected by the RIB to be the destination of all traffic that is categorized by that prefix. If, say, the 2 /24's that make up a /23 are both injected into the RIB, then all traffic destined to that /23 is now directed instead to the /24 MRS's.

Historically, there has been little to nothing to prevent this from happening at a global level. As we spoke about in the Day 12: ITSM Vulnerability Assessment Techniques post, even YouTube was recently hijacked by Pakistan using the exact concepts above.

Note that this is different than regular IP/ASN hijacking. The YouTube incident was BGP traffic hijacking. The difference (and they are even worse when combined) is that IP/ASN hijacking involves modifying the RIR (Regional Internet Registry) database records to new information, such as contact, DNS, RWhois, and other ownership rights. The world was first officially introduced to this style of attack in 1999 when CERT released an advisory detailing the Potential for False Authentication in Registry Transactions aka the "MAIL-FROM:" attack, which works just like regular domain hijacking.

Typically, the defense to these types of attacks has had one major stop-gap: ISP filtering, in particular -- customer filtering, which is typically/historically applied only on the customers. When L0pht presented to Congress in 1998 and told them that they could "take down the entire Internet in 30 minutes or less" -- Mudge and company were likely referring to the fact that route filters were applied at the customer level (and not even always there), but not in between ISP peering relationships.

Route-filters on ISP peering, especially "default-free zone" (DFZ) peering, often used the IRR (Internet Routing Registry) information to build a preventative measure. Hoewver, the IRR system itself (the primary vendor/organization being the RADB -- or the Routing Arbiter Database, or now known as the "Router Assets Database") was typically vulnerable to the same "false authentication" attack and other abuses such as social engineering.

RPKI looks like it goes a long way towards ensuring an easy path for ISP's and other BGP-speaking organizations to protect their routes and deliver an infrastructure that could withstand simple attack vectors such as these.

Posted by Dre on Wednesday, May 7, 2008 in Defense and Security.

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