Amazon recently lost control of the IP addresses it uses to host cloud services and took more than three hours to regain control, a time that allowed hackers to steal $235,000 in cryptocurrency from the users of one of the customers. affected, an analysis shows.
Hackers took control of approximately 256 IP addresses using BGP hijacking, a form of attack that exploits known weaknesses in a core Internet protocol. Short for border gateway protocol, BGP is a technical specification that organizations that route traffic, known as autonomous system networks, use to interoperate with other ASNs. Despite its crucial role in routing vast amounts of data around the world in real time, BGP still relies heavily on the Internet equivalent of word of mouth for organizations to track which IP addresses legitimately belong to which ASNs.
A case of mistaken identity
Last month, autonomous system 209243, which belongs to UK-based network operator Quickhost.es, suddenly began advertising that its infrastructure was the proper route for other ASNs to access what is known as the /24 block of IP addresses belonging to AS16509, one of at least three ASNs operated by Amazon. The hijacked block included 126.96.36.199, an IP address hosting cbridge-prod2.celer.network, a subdomain responsible for serving a critical smart contract user interface for the Celer Bridge cryptocurrency exchange.
On August 17, the attackers used hijacking to first obtain a TLS certificate for cbridge-prod2.celer.network, as they were able to prove to the GoGetSSL certificate authority in Latvia that they had control over the subdomain. Possessing the certificate, the hijackers hosted their own smart contract on the same domain and waited for visits from people trying to access the real Celer Bridge page cbridge-prod2.celer.network.
In all, the malicious contract drained a total of $234,866.65 from 32 accounts, according to it is written from the Coinbase threat intelligence team.
Coinbase team members explained:
The phishing contract closely resembles the official Celer Bridge contract by mimicking many of its attributes. For any method not explicitly defined in the phishing contract, it implements a proxy structure that forwards calls to the legitimate Celer Bridge contract. The proxy contract is unique for each chain and is configured at initialization. The following command illustrates the content of the storage slot responsible for the phishing contract proxy configuration:
The phishing contract steals user funds using two approaches:
- All tokens passed by phishing victims are drained using a custom method with a 4-byte value 0x9c307de6()
- The phishing contract overrides the following methods designed to immediately steal a victim’s tokens:
- send() – used to steal tokens (eg USDC)
- sendNative() – used to steal native assets (e.g. ETH)
- addLiquidity() – used to steal tokens (eg USDC)
- addNativeLiquidity() – used to steal native assets (eg ETH)
Below is a sample reverse engineered snippet that redirects assets to the attacker’s wallet: