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V-251571

CAT II (Medium)

Firefox deprecated ciphers must be disabled.

Rule ID

SV-251571r960963_rule

STIG

Mozilla Firefox Security Technical Implementation Guide

Version

V6R7

CCIs

CCI-000381

Discussion

A weak cipher is defined as an encryption/decryption algorithm that uses a key of insufficient length. Using an insufficient length for a key in an encryption/decryption algorithm opens up the possibility (or probability) that the encryption scheme could be broken.

Check Content

Type "about:policies" in the browser address bar.

If "DisabledCiphers" is not displayed under Policy Name or the Policy Value is not "TLS_RSA_WITH_3DES_EDE_CBC_SHA" with a value of  "true", this is a finding.

Fix Text

Windows group policy:
1. Open the group policy editor tool with "gpedit.msc".
2. Navigate to Policy Path: Computer Configuration\Administrative Templates\Mozilla\Firefox\Disabled Ciphers
Policy Name: TLS_RSA_WITH_3DES_EDE_CBC_SHA
Policy State: Enabled

macOS "plist" file:
Add the following:
<key>DisabledCiphers</key>
  <dict>
    <key>TLS_RSA_WITH_3DES_EDE_CBC_SHA</key>
    <true/>
  </dict>

Linux "policies.json" file:
Add the following in the policies section:
"DisabledCiphers": {
  "TLS_RSA_WITH_3DES_EDE_CBC_SHA": true
}