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ConfigProof

All controls

ASA-MGT-007MediumCisco ASA

SSH key exchange with SHA-1

At a glance

Base severity

Medium

Area

Administrators and Access

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

SHA-1 based key exchange is deprecated; current clients refuse it or warn.

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 > Device Management > Management Access > ASDM/HTTPS/Telnet/SSH > SSH Settings, set the Diffie-Hellman Key Exchange to Group 14 SHA256. Apply and save.
  2. On the CLI: ssh key-exchange group dh-group14-sha256, and write memory.

Command line

Cisco ASA CLI

configure terminalssh key-exchange group dh-group14-sha256endwrite 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 ssh
Before you type it2
  • 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>).

How to confirm the fix

  • Run show ssh and connect with a current client.

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.

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