Security Experts:

Connect with us

Hi, what are you looking for?

SecurityWeekSecurityWeek

Vulnerabilities

Avast AntiTrack Flaw Allows MitM Attacks on HTTPS Traffic

A vulnerability in Avast’s anti-tracking solution could allow malicious actors to perform man-in-the-middle (MitM) attacks on HTTPS traffic, a security researcher has discovered.

The security flaw, which impacts both Avast and AVG AntiTrack, as they share underlying code, resides in the manner in which the software filters HTTPS traffic.

A vulnerability in Avast’s anti-tracking solution could allow malicious actors to perform man-in-the-middle (MitM) attacks on HTTPS traffic, a security researcher has discovered.

The security flaw, which impacts both Avast and AVG AntiTrack, as they share underlying code, resides in the manner in which the software filters HTTPS traffic.

Moreover, with the feature enabled, a browser could successfully connect using TLS 1.0, even if the old security protocol had been explicitly disabled in the browser.

The bug could be triggered without performing any special action, using AntiTrack in its default configuration, web designer and security consultant David Eade reveals.

Eade discovered that AntiTrack proxies traffic to HTTPS sites using its own certificates, after adding its own certificate (named “AvastAntiTrack 2”) to the Windows “Trusted Root Certification Authorities” store at installation.

The solution presents the browser with a certificate of its own for each website visited, and the user is shown a secure padlock icon when navigating to the site, although traffic is not protected to the end web server, the researcher says.

According to Eade, Avast AntiTrack fails to check the validity of web server certificates, which makes it easy for an MitM attacker to serve a fake site using a self-signed certificate. While the attack should not work under normal circumstances, AntiTrack’s proxy ignores the certificate problem and presents to the victim its own certificate, which is trusted by the victim’s browser.

The anti-tracking solution also downgrades the browser’s security protocol to TLS 1.0, even if the application was configured to use only TLS 1.2 or higher — as is the case with Internet Explorer and Microsoft Edge.

On top of that, the researcher discovered that AntiTrack does not honor browser cipher suites and ignores them in favor of older, weaker ciphers. Furthermore, the solution does not support Forward Secrecy.

Tracked as CVE-2020-8987, the issues were reported to Avast in August last year and were fixed with the release of Avast AntiTrack version 1.5.1.172 and AVG AntiTrack version 2.0.0.178 in late February and early March 2020, respectively.

Related: Vulnerabilities Disclosed in Kaspersky, Trend Micro Products

Related: Avast, Avira Products Vulnerable to DLL Hijacking

Related: Avast Discloses New Supply-Chain Attack Attempt

Written By

Ionut Arghire is an international correspondent for SecurityWeek.

Click to comment

Daily Briefing Newsletter

Subscribe to the SecurityWeek Email Briefing to stay informed on the latest threats, trends, and technology, along with insightful columns from industry experts.

Join this webinar to learn best practices that organizations can use to improve both their resilience to new threats and their response times to incidents.

Register

Join this live webinar as we explore the potential security threats that can arise when third parties are granted access to a sensitive data or systems.

Register

Expert Insights

Related Content

Vulnerabilities

Less than a week after announcing that it would suspended service indefinitely due to a conflict with an (at the time) unnamed security researcher...

Risk Management

The supply chain threat is directly linked to attack surface management, but the supply chain must be known and understood before it can be...

Vulnerabilities

Apple has released updates for macOS, iOS and Safari and they all include a WebKit patch for a zero-day vulnerability tracked as CVE-2023-23529.

Application Security

Drupal released updates that resolve four vulnerabilities in Drupal core and three plugins.

Cloud Security

VMware vRealize Log Insight vulnerability allows an unauthenticated attacker to take full control of a target system.

IoT Security

Lexmark warns of a remote code execution (RCE) vulnerability impacting over 120 printer models, for which PoC code has been published.

Application Security

A CSRF vulnerability in the source control management (SCM) service Kudu could be exploited to achieve remote code execution in multiple Azure services.

Vulnerabilities

GoAnywhere MFT users warned about a zero-day remote code injection exploit that can be targeted directly from the internet