Spamhaus and SpamCop serve as blocklist generators for mail servers all over the internet. They both deal with the unwanted spam that affects users, much of which is fairly innocuous.

But since cybercriminals do generate spam as part of their attachment-spreading campaigns, keeping spam under control means avoiding spam network hijacking.

Spam Network Hijacking Spikes

Spamhaus recently warned that it observed a spike in network hijacking in support of spam campaigns. Specifically, the company is most concerned about the Border Gateway Protocol (BGP) hijacking it detected, Softpedia reported.

This type of hijack causes an internet service provider (ISP) to falsely announce to all other service providers that an IP range has been found on its network. The ISP can then receive the traffic destined for that range of IP. Perhaps more importantly to the spammer, it can send traffic that uses the IP address space of the hijacked network.

Spamhaus has seen this activity grow over the last three years, but the impetus for the growth may not be readily apparent. One reason for the rise in hijacking is the shrinking pool of IPv4 addresses available to spammers. If a blocking service bans a spamming address, the spammer has limited choices with which to replace it.

It seems that BGP hijackers like to take over legacy IP ranges. The true legacy owners may not care about their IPv4 space anymore, making them an easy target.

Spam Wars in Full Swing

Softpedia further noted that the American Registry for Internet Numbers (ARIN) had similarly sounded the alarm in June about an increase in IPv4 range hijacks. The group said that criminals were registering fake companies or re-registering old domain names without the authority to take over the older IPv4 ranges.

As the spam wars reignite, alternative methods of spam determination may prove useful when a blocklist alone isn’t enough.