A vulnerability has been discovered in Hotspot Shield's Windows VPN client that could allow for privilege escalation if exploited by an attacker.
The vulnerability, tracked as CVE-2020-17365, was discovered by researcher Chen Erlich at the security firm Cympton and it is the result of improper directory permissions in versions 10.3.0 and earlier of the HotSpot Shield's VPN client for Windows.
An attacker could exploit this vulnerability to corrupt system files by creating a specially crafted symbolic link to a critical file on a user's system and overwrite it with privileges of the application.
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Privilege escalation vulnerability
In a security update page on its site, Hotspot Shield's parent company Pango explained that a vulnerability was initially reported in the VPN company's 10.0.1 Windows client.
The Hotspot Shield Service has system level privileges and writes log files into the folder with local user permissions. As a result of this, removing the folder and abusing NTFS junctions can allow an unprivileged user to write to any file on the file system with SYSTEM privileges.
In a blog post about the privilege escalation vulnerability he discovered, Erlich explained how to mitigate it, saying: “This vulnerability can be mitigated by applying accurate ACL permissions to any location where actions are performed by privileged processes, including C:\ProgramData\Hotspot Shield\logs.”
Thankfully though, HotSpot Shield users won't have to do this as the company has released an updated version of its Windows client (version 10.6.0) that patches the vulnerability.
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