Kaspersky has patched several vulnerabilities affecting the web protection features present in its Anti-Virus, Internet Security, Total Security, Free Anti-Virus, Security Cloud, and Small Office Security products.
Researcher Wladimir Palant informed Kaspersky in December 2018 that he had found some vulnerabilities related to product features designed to block ads and trackers and warn users when a search result might be malicious.
The problem was related to the way Kaspersky products monitor websites for potential threats when users don’t install an optional browser extension that is designed for this task. If the extension is not installed, in order to still provide protection to users, Kaspersky products inject scripts into visited web pages.
Palant found that the secret value used to protect the communications between the injected scripts and the application could have been easily obtained, allowing an attacker to send arbitrary commands to the application. The researcher showed how a website could leverage this method to silently disable ad blocking and tracking protection.
Kaspersky informed the researcher in July 2019 that it had patched the issues, but Palant discovered that the fix, which prevented websites from disabling ad blocking and tracking protection, actually “made things worse.”
One of the new flaws could have been exploited to collect information about the system, such as Windows version and the customer’s unique ID. This issue was similar to one found earlier this year by Ronald Eikenberg, who showed that a unique device ID could be leveraged to track users online.
The expert also discovered a denial-of-service (DoS) vulnerability that could have been exploited by malicious websites to crash the antivirus process, leaving the system unprotected.
In a blog post published on Monday, Kaspersky revealed how its technology works and said it had patched all the vulnerabilities. Palant has confirmed that the security flaws have been mostly fixed, but pointed out that websites can still send some commands to the Kaspersky apps and some of these commands might not be harmless. However, he admits that he has not analyzed all of the functionality to determine its potential security impact.
According to Kaspersky’s advisory, one flaw also affected the Protection extension for Chrome. This weakness allowed an attacker to remotely remove other installed extensions.
In the impacted 2019 products and version 6 of Small Office Security, Kaspersky fixed the vulnerabilities with Patch I and Patch J. In the 2020 products and version 7 of Small Office Security, the fixes are included in Patch E and Patch F.
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