Bug ID 597797: Allow users to disable enforcement of RFC 7507 Fallback SCSV

Last Modified: Nov 07, 2022

Bug Tracker

Affected Product:  See more info
BIG-IP LTM(all modules)

Known Affected Versions:
11.6.0, 11.6.0 HF1, 11.6.0 HF2, 11.6.0 HF3, 11.6.0 HF4, 11.6.0 HF5, 11.6.0 HF6, 11.6.0 HF7, 11.6.0 HF8, 11.6.1, 11.6.1 HF1, 12.0.0, 12.0.0 HF1, 12.0.0 HF2, 12.0.0 HF3, 12.0.0 HF4, 12.1.0, 12.1.0 HF1, 12.1.0 HF2, 12.1.1, 12.1.1 HF1, 12.1.1 HF2, 12.1.2

Fixed In:
13.0.0, 12.1.2 HF1, 11.6.1 HF2

Opened: Jun 07, 2016
Severity: 3-Major
Related Article:
K78449695

Symptoms

When RFC 7507 (fallback SCSV) was implemented, some BIG-IP administrators found their TLS/SSL clients were incompatible and could no longer connect to the BIG-IP system.

Impact

Inability to support connections from older TLS/SSL clients that are unable to use the more recent (and more secure) TLS/SSL protocols.

Conditions

Client software that attempts to connect to a virtual server using an older, less secure version of the TLS/SSL protocol, for instance, TLS 1.0.

Workaround

There is no workaround.

Fix Information

When SSL.fallback_SCSV is set to disable, the RFC 7507 implementation will be disabled, though it must be acknowledged that this introduces a security hole when negotiating SSLv3.

Behavior Change

When RFC 7507 was implemented, some BIG-IP administrators found that their SSL clients were incompatible. This change introduces a bigdb variable (SSL.fallback_SCSV) to disable this.