11/3/2022 0 Comments Nhl 2004 rebuilt 2015 101 pbpBut its existence is not important here because the purpose of the img element is to acquire a legitimate certificate, which has been cached in the browser now. After the browser receives a legitimate certificate from the HTTPS server (step 4), it will try to retrieve a.jpg, which may or may not exist on the server (not shown in the figure). The request is permitted by the proxy at this time. In order to get a.jpg, the browser initiates an SSL handshake with the HTTPS server. But before the redirection, the following steps happen subsequently: the img element requests an image from (step 3). The meta element will redirect the browser to after one second. The attack works as follows: when a browser issues a request for (step 1), the proxy returns an HTTP 502 message (or any other 4xx/5xx message) that contains a meta element and an img element (step 2). (Note that Safari always displays the lock icon when the address bar has an HTTPS URL, even without a cached certificate, so Safari is a trivial target of the spoofing attack.) PayPal represents an arbitrary website.) IE, Opera and Chrome, but not Firefox, are vulnerable to this attack. Figure 4 illustrates how a proxy certifies a fake login page by taking advantage of a cached certificate of from a previous SSL handshake. This fix would not block the attack that we describe below, which does not involve any script. The proposal was based on the consideration that benign proxy error messages are valuable for troubleshooting network problems, but there is no compelling reason to allow scripts in error messages. When we reported this issue to a browser vendor, one of the vendor’s proposed fixes was to disable scripts in any 4xx/5xx error-response pages, and only render static HTML contents. The script will run in the HTTPS context of the victim server and compromise the confidentiality. In Section III.A, we have seen that the PBP proxy can supply a script in an error-response. Certifying a Proxy Page with a Real Certificate In the second attack, the proxy can authenticate to the HTTPS server as a logon user.Ī. In the first attack, the proxy’s own page can be certified with the trusted certificate of the HTTPS server that the browser intends to communicate. They target the authentication mechanisms in browsers. In this section, we show two attacks that can be accomplished entirely by static HTML contents. When a class of security problems is not always script-related, defense solutions should be explored more broadly. Typically, for script-based security issues, the defense solutions are along the line of disabling, filtering, or guarding scripts. Nevertheless, in order to better understand the potential threat of PBP, thinking beyond script-based attacks is very important. By running malicious scripts in the context of victim HTTPS domains, these attacks can access or alter sensitive data that are supposed to be protected by HTTPS. We just described a number of script-based attacks that violate the same-origin policy.
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