How to secure your Mozilla Firefox browser in Ubuntu 18.04 LTS

Posted: 2018/09/25 in Security, Ubuntu
Tags: , , , ,

Please first visit this bug report that I filed:

So disabling the cipher suites below in Mozilla Firefox will make certain websites inaccessible, but will make the browsing experience more secure.

It is up to you to decide if you want extra security or not.

If you wish to proceed, visit following website to test the weaknesses in your Mozilla Firefox browser:

Then upgrade Mozilla Firefox to the latest version.

In Mozilla Firefox, navigate to   “about:config”

Set security.tls.version.max to 4

Set security.tls.version.min to 3

Set security.ssl3.rsa_aes_128_sha to false

Set security.ssl3.rsa_aes_256_sha to false

Set security.ssl3.rsa_des_ede3_sha to false

Go back to this website to retest weaknesses:

After the changes above, only following Protocols and Cipher Suites should be supported by Mozilla Firefox.

HTTPS protocols TLS 1.0 and older are known to be weak and should be disabled as described above.

TLS_RSA_*_CBC_SHA Cipher Suites should not be used anymore, as they are considered weak. But disabling them will make certain websites inaccessible.

TLS 1.3 Yes
TLS 1.2 Yes


Cipher Suites (in order of preference)
TLS_AES_128_GCM_SHA256 (0x1301)   Forward Secrecy 128
TLS_CHACHA20_POLY1305_SHA256 (0x1303)   Forward Secrecy 256
TLS_AES_256_GCM_SHA384 (0x1302)   Forward Secrecy 256
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 (0xc02b)   Forward Secrecy 128
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (0xc02f)   Forward Secrecy 128
TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 (0xcca9)   Forward Secrecy 256
TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 (0xcca8)   Forward Secrecy 256
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 (0xc02c)   Forward Secrecy 256
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (0xc030)   Forward Secrecy 256
TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (0xc013)   Forward Secrecy 128
TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (0xc014)   Forward Secrecy 256

Further instructions (more extensive) can be found here:

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