Enforcing the First AS in BGP AS_PATHs

BGP route hijacks using forged AS_PATH information are analyzed, showing how attackers can misdirect traffic and conceal identity.

• •Attackers forge complete AS_PATH information by including fake upstream networks without their own ASN
• •First AS checking verifies that the leftmost AS in AS_PATH matches the peer's ASN as defined in RFC 4271
• •Two attack vectors: forged origin attacks (stripping AS from path) and AS_PATH shortening to artificially attract traffic
• •ASPA cannot prevent these attacks if sufficient AS_PATH information is lacking due to forged announcements
• •Testing revealed many Tier 1 networks fail to enforce First AS verification, allowing hijacked routes to propagate

This summary was automatically generated by AI based on the original article and may not be fully accurate.