The Cloudflare WARP client for Windows assigns loopback IPv4 addresses for the DNS Servers, since WARP acts as local DNS server that performs DNS queries in a secure manner, however, if a user is connected to WARP over an IPv6-capable network, te WARP client did not assign loopback IPv6 addresses but Unique Local Addresses, which under certain conditions could point towards unknown devices in the same local network which enables an Attacker to view DNS queries made by the device.
Cloudflare WARP client for Windows (up to v2023.3.381.0) allowed a malicious actor to remotely access the warp-svc.exe binary due to an insufficient access control policy on an IPC Named Pipe. This would have enabled an attacker to trigger WARP connect and disconnect commands, as well as obtaining network diagnostics and application configuration from the target's device. It is important to note that in order to exploit this, a set of requirements would need to be met, such as the target's device must've been reachable on port 445, allowed authentication with NULL sessions or otherwise having knowledge of the target's credentials.
Due to a hardlink created in the ProgramData folder during the repair process of the software, the installer (MSI) of WARP Client for Windows (<= 2022.12.582.0) allowed a malicious attacker to forge the destination of the hardlink and escalate privileges, overwriting SYSTEM protected files.
As Cloudflare WARP client for Windows (up to version 2022.5.309.0) allowed creation of mount points from its ProgramData folder, during installation of the WARP client, it was possible to escalate privileges and overwrite SYSTEM protected files.
An unprivileged (non-admin) user can exploit an Improper Access Control vulnerability in the Cloudflare WARP Client for Windows (<= 2022.12.582.0) to perform privileged operations with SYSTEM context by working with a combination of opportunistic locks (oplock) and symbolic links (which can both be created by an unprivileged user).
After installing the Cloudflare WARP Client (admin privileges required), an MSI-Installer is placed under C:\Windows\Installer. The vulnerability lies in the repair function of this MSI.
ImpactAn unprivileged (non-admin) user can exploit this vulnerability to perform privileged operations with SYSTEM context, including deleting arbitrary files and reading arbitrary file content. This can lead to a variety of attacks, including the manipulation of system files and privilege escalation.
PatchesA new installer with a fix that addresses this vulnerability was released in version 2023.3.381.0. While the WARP Client itself is not vulnerable (only the installer), users are encouraged to upgrade to the latest version and delete any older installers present in their systems.
support_uri parameter in the WARP client local settings file (mdm.xml) lacked proper validation which allowed for privilege escalation and launching an arbitrary executable on the local machine upon clicking on the "Send feedback" option. An attacker with access to the local file system could use a crafted XML config file pointing to a malicious file or set a local path to the executable using Cloudflare Zero Trust Dashboard (for Zero Trust enrolled clients).
Using warp-cli command "add-trusted-ssid", a user was able to disconnect WARP client and bypass the "Lock WARP switch" feature resulting in Zero Trust policies not being enforced on an affected endpoint.
It was possible to bypass policies configured for Zero Trust Secure Web Gateway by using warp-cli 'set-custom-endpoint' subcommand. Using this command with an unreachable endpoint caused the WARP Client to disconnect and allowed bypassing administrative restrictions on a Zero Trust enrolled endpoint.
By using warp-cli subcommands (disable-ethernet, disable-wifi), it was possible for a user without admin privileges to bypass configured Zero Trust security policies (e.g. Secure Web Gateway policies) and features such as 'Lock WARP switch'.
Cloudflare WARP client for Windows (up to v. 2022.5.309.0) allowed creation of mount points from its ProgramData folder. During installation of the WARP client, it was possible to escalate privileges and overwrite SYSTEM protected files.