Cybersecurity researchers are warning that CAPTCHA-breaking services are being offered for sale to bypass systems designed to distinguish legitimate users from bot traffic.
These services work by farming out CAPTCHA-breaking tasks to actual human solvers. This makes it easy for customers of CAPTCHA-breaking services to develop automated tools against online web services. And because actual humans are solving CAPTCHAs, the purpose of filtering out automated bot traffic through these tests are rendered ineffective.
Threat actors have also been observed purchasing CAPTCHA-breaking services and combining them with proxyware offerings to obscure the originating IP address and evade antibot barriers.
Proxyware, although marketed as a utility to share a user’s unused internet bandwidth with other parties in return for a “passive income,” essentially turns the devices running them into residential proxies.
In one instance of a CAPTCHA-breaking service targeting popular social commerce marketplace Poshmark, the task requests emanating from a bot are routed via a proxyware network.
“CAPTCHAs are common tools used to prevent spam and bot abuse, but the increasing use of CAPTCHA-breaking services has made CAPTCHAs less effective,” said security researcher Joey Costoya. “While online web services can block abusers’ originating IPs, the rise of proxyware adoption renders this method as toothless as CAPTCHAs.”
To mitigate such risks, online web services are recommended to supplement CAPTCHAs and IP blocklisting with other anti-abuse tools.
Here are some additional tips for mitigating the risks posed by CAPTCHA-breaking services:
- Use a variety of anti-abuse tools, including CAPTCHAs, IP blocklisting, and anomaly detection.
- Monitor your traffic for signs of abuse, such as unusual spikes in traffic or requests from unusual IP addresses.
- Keep your software up to date with the latest security patches.
- Train your staff to be aware of the signs of abuse and how to report it.