SB2021051240 - SUSE update for openvpn
Published: May 12, 2021
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 2 secuirty vulnerabilities.
1) Resource management error (CVE-ID: CVE-2020-11810)
The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to improper management of internal resources within the application that allows a timing attack to be carried out against OpenVPN clients.
An attacker can inject a data channel v2 (P_DATA_V2) packet using a victim's peer-id. Normally such packets are dropped, but if this packet arrives before the data channel crypto parameters have been initialized, the victim's connection will be dropped. This requires careful timing due to the small time window (usually within a few seconds) between the victim client connection starting and the server PUSH_REPLY response back to the client. This attack will only work if Negotiable Cipher Parameters (NCP) is in use.
2) Improper authentication (CVE-ID: CVE-2020-15078)
The vulnerability allows a remote attacker to bypass authentication process.
The vulnerability exists due to an error in when processing authentication requests. A remote attacker can bypass authentication and access control channel data on servers configured with deferred authentication, which can be used to potentially trigger further information leaks.
Under certain circumstances an attacker can trick the server using delayed authentication (plugin or management) into returning a PUSH_REPLY before the AUTH_FAILED message, which can possibly be used to gather information about a VPN setup. In combination with "--auth-gen-token" or a user-specific token auth solution it can be possible to get access to a VPN with an otherwise-invalid account.
Remediation
Install update from vendor's website.