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ConfigProof

All controls

ASA-SEC-001CriticalCisco ASA

Inbound entry allows any destination or any service

At a glance

Base severity

Critical

Area

Security Policies

Platform

Cisco ASA

Evidence level

Derived0.90

Benchmark reference

Reads the export, not the device

ConfigProof reads a configuration export. This control is evaluated against the objects in that file, and it reports what the file says. It does not connect to the device and sees no traffic, so a finding here describes the configuration, not what the firewall is doing right now.

Why it matters

A permit from the internet side to every internal address exposes each host behind the firewall to whatever the entry's service allows.

How to fix it

Web interface

The steps below are written for the web interface. A finding raised on your own export carries the same steps with your object names filled in.

  1. In ASDM: Configuration > Firewall > Access Rules, select the rule, Edit, and narrow Destination and Service to the published hosts and ports, or delete it. Apply, then File > Save Running Configuration to Flash.
  2. On the CLI: remove the entry with no access-list <list> extended permit ..., then add the scoped entry with access-list <list> line <n> extended permit tcp any object <server> eq <port>, and write memory.

Command line

Cisco ASA CLI

configure terminalno access-list <access-list> line <line> <entry>access-list <access-list> line <line> <scoped-entry>endwrite memory

An example. Values in angle brackets are yours to supply; a finding on your own export fills in the names it read. Typed in configuration mode; write memory saves it, with no separate commit. Read every line first.

Read it back

show access-list <access-list>
Values to fill in4
<access-list>
The access list
<line>
The entry's line number in the list
<entry>
The entry's text after the line number, as the device shows it
<scoped-entry>
The narrowed entry: the sources, destinations and services that are needed
Before you type it3
  • Written from the ASA 9.x command reference and not run on a device: read each line before you paste it.
  • In multiple context mode, type it in the context it applies to (changeto context <name>).
  • Narrowing this changes who reaches what. Confirm the new set covers the traffic the application needs.

How to confirm the fix

  • Run show access-list <list> and confirm the broad entry is gone and the scoped one is in place.

Limits

  • No limitation is recorded for this control beyond the one that applies to all of them: it reads a configuration export.

Compliance references

No benchmark recommendation is mapped to this control in this version.

More in Security Policies

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