Search Redirection and the Illicit Online Prescription Drug Trade
Really interesting research.
Search-redirection attacks combine several well-worn tactics from black-hat SEO and web security. First, an attacker identifies high-visibility websites (e.g., at universities) that are vulnerable to code-injection attacks. The attacker injects code onto the server that intercepts all incoming HTTP requests to the compromised page and responds differently based on the type of request:
Requests from search-engine crawlers return a mix of the original content, along with links to websites promoted by the attacker and text that makes the website appealing to drug-related queries.
- Requests from users arriving from search engines are checked for drug terms in the original search query. If a drug name is found in the search term, then the compromised server redirects the user to a pharmacy or another intermediary, which then redirects the user to a pharmacy.
- All other requests, including typing the link directly into a browser, return the infected website’s original content.
- The net effect is that web users are seamlessly delivered to illicit pharmacies via infected web servers, and the compromise is kept hidden from view of the affected host’s webmaster in nearly all circumstances.
Upon inspecting search results, we identified 7,000 websites that had been compromised in this manner between April 2010 and February 2011. One quarter of the top ten search results were observed to actively redirect to pharmacies, and another 15% of the top results were for sites that no longer redirected but had previously been compromised. We also found that legitimate health resources, including authorized pharmacies, were largely crowded out of the top results by search-redirection attacks and blog and forum spam promoting fake pharmacies.
And the paper.
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