CVE-2020-25779 in Trend Micro
Summary
by MITRE • 10/14/2020
Trend Micro Antivirus for Mac 2020 (Consumer) has a vulnerability in which a Internationalized Domain Name homograph attack (Puny-code) could be used to add a malicious website to the approved websites list of Trend Micro Antivirus for Mac to bypass the web threat protection feature.
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Analysis
by VulDB Data Team • 11/19/2020
The vulnerability identified as CVE-2020-25779 represents a significant security flaw in Trend Micro Antivirus for Mac 2020 consumer edition that leverages internationalized domain name homograph attacks through punycode encoding. This weakness allows attackers to exploit the DNS resolution process by presenting malicious websites with domain names that appear visually identical to legitimate sites but are actually different at the character level. The vulnerability specifically targets the web threat protection feature of the antivirus software, which maintains a whitelist of approved websites that bypass certain security checks. When a user encounters a malicious website that has been encoded using punycode to disguise its true identity, the system may incorrectly classify it as a legitimate site due to the homograph attack's visual similarity to trusted domains.
The technical implementation of this vulnerability stems from the antivirus software's insufficient validation of internationalized domain names during the approval process. When users add websites to the approved list, the software fails to properly verify the authenticity of the domain name against its encoded representation. This occurs because the application does not implement proper unicode normalization or domain validation checks that would detect when a seemingly benign domain name actually contains hidden unicode characters that render it as a different string when converted to punycode format. The flaw essentially allows attackers to create deceptive domain names that appear legitimate in the user interface but are actually malicious when processed through the underlying DNS resolution mechanisms.
The operational impact of this vulnerability extends beyond simple bypass of web protection features to potentially enable sophisticated phishing attacks and malware distribution. Attackers can craft domain names that visually mimic well-known websites such as banks, social media platforms, or government portals, tricking users into adding these malicious domains to their approved list. Once added, these sites can bypass Trend Micro's web threat protection, allowing attackers to deliver malware, steal credentials, or conduct other malicious activities without detection. This creates a dangerous scenario where users' trust in the antivirus software is undermined, as the very protection mechanism designed to keep them safe becomes compromised through this homograph attack vector.
The vulnerability aligns with CWE-1004 which addresses insecure default permissions and improper handling of internationalized domain names in security contexts. This weakness also maps to ATT&CK technique T1071.004 which covers application layer protocol: DNS and T1566.001 which involves phishing through social engineering. Organizations using Trend Micro Antivirus for Mac 2020 consumer edition face significant risk exposure, as this vulnerability can be exploited without requiring advanced technical skills from attackers. The attack surface is particularly concerning given that users often add websites to approved lists for convenience, making this a persistent threat vector that can be exploited through social engineering or automated attacks.
Mitigation strategies for this vulnerability should include immediate software updates from Trend Micro to address the domain validation flaw, implementation of additional domain checking mechanisms, and user education regarding the risks of adding unfamiliar websites to approved lists. System administrators should consider implementing network-level monitoring to detect suspicious domain name patterns and establish policies that require verification of domain legitimacy before adding sites to approved lists. The remediation process must address both the immediate technical fix within the antivirus software and broader security awareness training to prevent users from inadvertently enabling these attacks through their own actions. Organizations should also consider implementing additional layers of web filtering or proxy services that can provide independent validation of domain names beyond what the antivirus software provides.