Malicious Proxy Auto-Config redirection

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Read More >> TechNet: Malicious Proxy Auto-Config redirection

Internet banking credentials are a desired target for cybercriminals. They can be targeted with man-in-the-middle attacks or through password stealing trojans such as Fareit, Zbot or Banker. A less known, yet commonly found in South America and to a lesser extent in Russia, method to gain unauthorized access to a user’s banking credentials is through malicious Proxy Auto-Config (PAC) files. Normally, PAC files offer similar functionality to the hosts file, allowing IP/website redirection, but only for the browser. Unfortunately, they can also be used for nefarious purposes.

When a user is infected with a malicious PAC and visits an internet banking website, the browser is usually redirected to a fake website that mimics the intended banking website. This may result in credentials being stolen - or worse, online account hijacking.

The most common infection scenario is shown in figure 1 below:
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One important user mitigation comes directly through the browser. What a user would experience when browsing the real website is shown below:
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Figure 3: Web page without PAC redirection

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Figure 4: Web page with malicious PAC redirection

You can see above that the original website has an authenticated certificate and appears in a green address bar. The original website is also using HTTPS (secure communication).

Read More >> TechNet: Malicious Proxy Auto-Config redirection
 
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