These are ignored by Avast Antitrack in favour of much older ciphers, considered weak by today's standards. Microsoft periodically updates the cipher suites available to Internet Explorer and Edge. Issue 3īrowser cipher suites are not honoured and Avast Antitrack's chosen cipher suites do not support Forward Secrecy. However, Avast Antitrack ignores this setting and makes connections with TLS 1.0 regardless (if the web server supports it), even if the web server supports TLS 1.2 too. Ordinarily this should mean these browser cannot reach websites using lower versions of TLS. Internet Explorer and Edge can be configured to use only TLS 1.2 or higher. Issue 2Īvast Antitrack downgrades the browser's security protocol to TLS 1.0. The "malicious" web server was configured with a self-signed certificate for Ordinarily this should not work for HTTPS traffic (because the browser would warn of an invalid certificate authority), but Avast Antitrack's proxy ignores the certificate problem and mints its own certificate to present to the victim (that is trusted by the victim's browser due to the entry in their Trusted Root Certification Authorities store). This was confirmed by capturing a victim's DNS requests on port 53 and responding with a "malicious" IP address for certain queries. This makes it trivial for a man-in-the-middle to serve a fake site using a self-signed certificate. Issue 1Īvast Antitrack does not check the validity of certificates presented by the end web server. The browser displays a secure padlock icon, but importantly traffic is not secured to the end web server. Presents the browser with a freshly minted certificate of its own forĮach site visited. "By default, the Trusted Root Certification Authorities certificate store is configured with a set of public CAs that has met the requirements of the Microsoft Root Certificate Program." Microsoft Īvast Antitrack then proxies its users' traffic to HTTPS sites and "AvastAntiTrack 2") to the Windows "Trusted Root Certification In depthĭuring installation, Avast Antitrack adds a certificate (named Refers to Avast Antitrack but applies equally to both products. Vendor acknowledgement: Researcher David Eade reports AntiTrack bug to AvastĪvast Antitrack and AVG Antitrack share core code. And the attacker does not need access to the victim's machine.Īffected Product(s): Avast Antitrack below 1.5.1.172, AVG Antitrack below 2.0.0.178. No special action is necessary by the victim using Avast Antitrack in its default configuration. If a site needs two factor authentication (such as a one-time password), then the attacker can still hijack a live session by cloning session cookies after the victim logs in. A remote attacker running a malicious proxy could capture their victim's HTTPS traffic and record credentials for later re-use.
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