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ConfigProof

All controls

ASA-SEC-003MediumCisco ASA

Interface with no inbound access list

At a glance

Base severity

Medium

Area

Interfaces and Segmentation

Platform

Cisco ASA

Evidence level

Fact1.00

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

Without an access list the ASA lets traffic from a higher security level to any lower one, so whatever the level allows is permitted by default rather than by a rule.

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 > Add, choose the interface, and add the rules it needs; ASDM creates and binds the list. Apply and save.
  2. On the CLI: access-list <nameif>-IN extended permit ..., then access-group <nameif>-IN in interface <nameif>, and write memory.

Command line

Cisco ASA CLI

configure terminalaccess-list <access-list> extended deny ip any any logaccess-group <access-list> in interface <nameif>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 running-config access-group
Values to fill in2
<access-list>
The access list
<nameif>
The interface name (nameif)
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>).
  • Add the rules the interface needs before binding the list: a bound list denies everything it does not permit.

How to confirm the fix

  • Run show running-config access-group and confirm the interface has a list.

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 Interfaces and Segmentation

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