Bulletproof Proxy Providers Try to Hide Botnet IP Address Needles in Haystacks

Cequence Security's CQ Prime research team thinks it has spotted a new trend it calls "bulletproof proxies." It's related to bulletproof hosting where providers offer considerable leniency in what content may be uploaded and distributed through their infrastructure and as well as protection from law enforcement investigations, information requests, subpoenas and the like. Take the same idea and apply it to a proxy hoster.

Bulletproof proxy providers will include millions of globally distributed residential IP addresses in their namespace that are marketed under the false pretenses of being used for legitimate purposes and aggressively compete against one another for their share of adversarial buyers, according to Cequence.

It also says in the report that attacks emanating from bulletproof proxy networks targeting Cequence financial services and retail customer environments increased 518% and 800% respectively between Q1-Q2 2019. They also say that more than 70% of the attack traffic across bulletproof proxy networks targeted mobile endpoints.

The inaugural analysis of automated malicious bot campaigns that Cequence performed was conducted across three industry verticals, where bulletproof proxies were found to be used as a means of distributing attacks globally across millions of high-reputation, residential IP addresses (such as routers, refrigerators, IoT devices, garage door motors and others).

Will Glazier, head of CQ Prime research, said that "The initial focus of CQ Prime will be research on the growing number of malicious, automated bot attacks and the four key components of each unique attack: user credentials, infrastructure, tools and behaviors. These attacks, which are nearly impossible to detect with legacy security tools, abuse business application logic, enabling bad actors to achieve various fraud and theft objectives."

These sort of proxy providers will support IPs that appear as coming from residential providers such as Comcast, AT&T, Bell and Vodafone. This organization of IP infrastructure will mess up defenders from being able to throw out defending responses aimed at particular IP blocks, networks or even individual IPs themselves. The same IP could be used for both legitimate and attacking transactions.

But in early May, they observed a large influx of attack traffic coming from Cogent Communications and Isomedia. The attack pattern spread across multiple customers. Further investigation revealed the traffic was being generated by the Bulletproof Proxy Provider SmartProxy. All told, they saw a 548% increase in traffic from these seemingly legitimate ISPs in a little less than a three-month period.

But to what end? Well, they went on to find use cases of social media automation, sneaker bots, ticket bots (both of which buy up merchandise to sell on the secondary market) and black hat SEO Optimization (to cause click fraud or undeserved ranking in search engines) tended to dominate the marketing material of these bulletproof proxy services.

Some metrics that might be used to detect abnormal bot activity that is using proxies may include changes in behavior and traffic distributions that deviate substantially from the norm. That may be expressed as login failure ratios, irregular fast POST patterns in a user session of a scraper, or irregular rotation and obfuscation among fields.

Bots are trying to camouflage themselves to make it harder to eradicate them. Spreading IP addresses globally is just one of the tricks that botmasters are employing, but one worthy of attention in a security posture.

— Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek.