Cisco ASA AnyConnect Brute Force Protection

Protect your Cisco ASA and Firepower VPN endpoints from brute force attacks with ThreatListPro's real-time IP blocklist. Works with FMC Security Intelligence, TID, and standalone ASA ACLs.

Start Blocking Attacks -- $9.99/mo
2M+
Malicious IPs Tracked
60s
Update Frequency
5 min
Setup Time

Cisco AnyConnect Under Siege

Cisco AnyConnect VPN is the most widely deployed enterprise VPN client in the world, making it a top target for credential-stuffing and brute force attacks.

The Scale of the Problem

Cisco ASA and FTD appliances running AnyConnect are attacked millions of times daily. Attackers use automated tools to cycle through stolen credential lists against the HTTPS-based login portal. Each attempt consumes CPU, memory, and VPN session resources on the ASA. Large-scale attacks can degrade VPN performance for legitimate users.

Network-Layer Blocking with ThreatListPro

ThreatListPro blocks known VPN attackers before they reach the AnyConnect portal. Using FMC's Security Intelligence feature or ASA ACLs, the blocklist drops traffic from attacker IPs at the network layer. No TLS negotiation, no XML login page served, no DAP evaluation -- the connection is silently dropped.

Cisco ASA / FTD Setup -- Step by Step

Choose the method that matches your deployment: FMC-managed FTD or standalone ASA.

01

Get Your ThreatListPro Feed URL

Sign up at threatlistpro.com and copy your unique feed URL from the dashboard:
https://feed.threatlistpro.com/v1/edl/YOUR_API_KEY

02

Option A: FMC Security Intelligence (FTD)

In Firepower Management Center, navigate to Intelligence > Sources > Collections. Click Add URL, paste your ThreatListPro feed URL, and set the update interval to 5 minutes. Then go to Policies > Access Control, click the Security Intelligence tab, and add the ThreatListPro source to the Block List for Network objects. Deploy to your FTD devices.

03

Option B: Standalone ASA with ACL

For standalone ASA without FMC, use a scheduled script to download the ThreatListPro feed and push it as a network object group via the ASA REST API:
POST /api/objects/networkobjectgroups
Reference the object group in an ACL applied to your outside interface:
access-list outside_in deny ip object-group ThreatListPro any

04

Option C: Threat Intelligence Director (TID)

If using FMC with TID enabled, navigate to Intelligence > Sources and add ThreatListPro as a flat file source with URL download. TID will automatically create observables and publish indicators to all managed sensors for blocking.

05

Verify Blocking

In FMC, check Analysis > Connection Events and filter by Security Intelligence action. For standalone ASA, review syslog messages with IDs 106023 (ACL deny) to confirm blocks. You should see traffic from ThreatListPro IPs being denied.

ThreatListPro vs. Alternatives

Compare automated VPN-focused blocking against other approaches for your Cisco environment.

FeatureThreatListProManual BlockingEnterprise Threat Feeds
VPN brute-force focused
Real-time updates (60s)
FMC Security Intelligence compatible
Standalone ASA support
Setup in under 5 minutes
Price$9.99/moStaff time$500+/mo

Frequently Asked Questions

How do I add an IP blocklist to Cisco ASA or FTD?

On Cisco FTD managed by FMC, use the Threat Intelligence Director (TID) to subscribe to ThreatListPro's feed or plaintext IP list. On standalone ASA, use a script to download the blocklist and push it as a network object group via the ASA REST API, then reference it in an ACL applied to the outside interface.

Does ThreatListPro protect against AnyConnect brute force attacks?

Yes. ThreatListPro blocks known brute force attacker IPs at the firewall level, before the AnyConnect SSL/TLS handshake occurs. This means attackers cannot reach the AnyConnect login page, attempt credentials, or consume ASA resources with failed authentication attempts.

Can I use ThreatListPro with Cisco Firepower Management Center (FMC)?

Yes. In FMC, navigate to Intelligence > Sources and add ThreatListPro as a flat file or URL-based source. FMC will download the list and distribute it to all managed FTD devices. You can also use Security Intelligence policies to apply the blocklist as a blacklist for incoming connections.

Protect Your Cisco VPN Infrastructure

Block brute force bots at the network layer. Works with ASA, FTD, and FMC.

Get ThreatListPro -- $9.99/mo

Works With All Major Firewalls

ThreatListPro provides a standard IP blocklist feed compatible with any firewall that supports external lists.

Palo Alto FortiGate pfSense OPNsense SonicWall Cisco ASA Sophos XG UniFi

Related Resources

Learn more about IP blocklists, VPN security, and how ThreatListPro compares to alternatives.

What Is an External Dynamic List (EDL)? VPN Brute Force Attacks Explained IP Blocklist vs Enterprise Threat Feed Stop Account Lockouts from Brute Force ThreatListPro vs FireHOL ThreatListPro vs AbuseIPDB Best VPN Brute Force Protection 2026 All Firewall Setup Guides