BGP Origin Hijacking: The 2008 BGP YouTube Outage from Pakistan to the world

 

Preface:

In February 2008 the world saw just how fragile and interconnected the Internet routing system is when Pakistan’s attempt to block YouTube locally ended up taking YouTube down globally. The Pakistani government asked local ISPs to block YouTube due to content, and Pakistan Telecom (AS17557) did so by announcing a false BGP route for YouTube’s IP prefix. This was meant to be a local announcement only but was accidentally propagated to the global Internet by their upstream provider PCCW (AS3491) who accepted and further announced the bogus route to other networks. Since BGP favors the most specific prefix, networks around the world started sending YouTube traffic to Pakistan Telecom and a massive black hole effect took YouTube down for users worldwide. This is often referred to as one of the biggest BGP hijacking incidents in history and showed the trust-based vulnerabilities in BGP, the lack of built in route authentication and the importance of implementing stronger security mechanisms like prefix filtering and RPKI to secure the global Internet.

What is BGP origin hijacking?

In BGP (Border Gateway Protocol), origin hijacking occurs when an Autonomous System (AS) announces an IP prefix it does not own.

When an AS originates a prefix, it claims to be the starting point (origin) for that IP address block. Other networks rely on these BGP announcements to build their routing tables and decide where to send traffic.

In origin hijacking, an AS (either by mistake or on purpose) announces a prefix that belongs to another AS. Since BGP has no authentication, most networks trust the announcement and traffic destined for the real owner gets redirected to the hijacker.

 How does it work?

• The legitimate owner of a prefix announces it to the Internet with its own AS number as the origin.
• An attacker AS (or a misconfigured AS) announces the same prefix or a more specific prefix but with itself as the origin AS.
• Because BGP prefers more specific prefixes and trusts shorter AS paths, routers around the world will start to prefer the hijacker’s route.
• As a result, traffic goes to the hijacker’s AS which can lead to:
• Traffic blackholing (dropping packets, outages)
• Traffic interception and monitoring (for spying or manipulation)
• Man-in-the-middle attacks

How to prevent BGP origin hijacking?

Preventing BGP origin hijacking is a top priority for the security and stability of the global Internet and requires a combination of technical measures, operational best practices and community coordination. The most basic step is to implement strict prefix filtering where ISPs and transit providers configure their routers to only accept and propagate route announcements that are explicitly authorized and expected from their customers and peers, thus preventing accidental or malicious advertisements of unwanted prefixes. In addition to prefix filtering, RPKI is a game changer; RPKI allows IP address holders to cryptographically sign Route Origin Authorizations (ROAs) which specify which Autonomous Systems (ASes) are allowed to originate specific prefixes and routers can validate these signatures to reject invalid announcements automatically. Beyond technical tools, operators should also keep their IRRs up to date so other networks can cross check route intentions and filter accordingly. Collaborative monitoring tools like BGPMon, RIPE RIS and MANRS (Mutually Agreed Norms for Routing Security) provide real time visibility into routing anomalies and can trigger rapid response to suspicious activity. And last but not least continuous operator education, strong operational security policies and community pressure to adopt routing security standards are key to strengthen the collective defense against hijacks. Although BGP was not designed with security checks in mind, widespread adoption of these best practices and technologies can reduce the risk of origin hijacking, protect critical Internet infrastructure and keep the trust and reliability on which global digital communication relies.

Conclusion:

In conclusion, the 2008 YouTube incident is an example of the dangers of the trust based global routing system, BGP, that allows a single misconfiguration or single malicious act to affect millions of users across the globe and critical online services.  This event shows the reliance upon the tenants of openness and cooperation that helped to create these very significant security risks, such as origin hijacking and ensuing outages, traffic interception or abuse of information. When considering building a 'solution' to try to reduce these risks, it cannot be solely a technical challenge and explicit responsibility lies with network operators to own the issue, and continue with best practices, such as prefix filtering, RPKI use, accurate Internet Routing Registry, real-time monitoring and alerts. In addition, in order to appreciate the heavier responsibility, there must be a culture of continual improvement, openness and respect of the collective responsibility across Internet space to establish a secure, stable, and resilient global network. As articulated above, through adhering to these best practices protocols and establishing collaborative and teamwork culture will assist in fortifying against future failures, while protecting global communications in a meaningful way and instilling the Internet as a trust platform for future innovation, connectivity and information exchanges.