Firefox deprecated ciphers must be disabled.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-251571 | FFOX-00-000027 | SV-251571r960963_rule | CCI-000381 | medium |
| Description | ||||
| 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. | ||||
| STIG | Date | |||
| Mozilla Firefox Security Technical Implementation Guide | 2025-02-11 | |||
Details
Check Text (C-251571r960963_chk)
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 (F-54960r820761_fix)
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
}