April 13, 2020

Playbook for VPN failed login attempts

By Sridhar Pippari


Remote work options—or telework—require an enterprise virtual private network (VPN) solution to connect employees to an organization’s information technology (IT) network.

Technical Details

The following are cybersecurity considerations regarding telework.

  • As organizations use VPNs for telework, more vulnerabilities are being found and targeted by malicious cyber actors.
  • As VPNs are 24/7, organizations are less likely to keep them updated with the latest security updates and patches.
  • Malicious cyber actors may increase phishing emails targeting teleworkers to steal their usernames and passwords.
  • Organizations that do not use multi-factor authentication (MFA) for remote access are more susceptible to phishing attacks.
  • Organizations may have a limited number of VPN connections, after which point no other employee can telework. With decreased availability, critical business operations may suffer, including IT security personnel’s ability to perform cybersecurity tasks.


Analyse the instancesof failed login from the last 5 minutes, 1 hour, or 24 hours. The results can be sorted by the number of instances a given user attempted to log in.

Record the date and time of each login attempt, the message explaining the reason each authentication failed e.g. a mismatched password, and the source IP address.




NIST Special Publication 800-46 v.2, Guide to Enterprise Telework, Remote Acces…
CISA Cyber Essentials
CERT/CC: VPN – A Gateway for Vulnerabilities
National Security Agency Cybersecurity Advisory: Mitigating Recent VPN Vulnerab…
CISA Insights: Risk Management for Novel Coronavirus (COVID-19)
Telework.gov Guidance

Blocking Brute Force Attack on GlobalProtect Portal Page


March 13, 2020: Initial Version