Bug 1335914

Summary:	Disable the MD5 as a signing algorithm in openssl library
Product:	Red Hat Enterprise Linux 6	Reporter:	Nikos Mavrogiannopoulos <nmavrogi>
Component:	openssl	Assignee:	Tomas Mraz <tmraz>
Status:	CLOSED ERRATA	QA Contact:	Stanislav Zidek <szidek>
Severity:	unspecified	Docs Contact:	Mirek Jahoda <mjahoda>
Priority:	unspecified
Version:	6.9	CC:	bk.aihg, szidek, tmraz
Target Milestone:	rc
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	openssl-1.0.1e-51.el6	Doc Type:	Deprecated Functionality
Doc Text:	MD5, MD4, and SHA0 as the signing algorithms in OpenSSL disabled With this update, support for the verification of MD5, MD4, and SHA0 signatures in certificates, Certificate Revocation Lists (CRL) and message signatures is removed. The system administrator can enable MD5, MD4, or SHA0 support by modifying the "LegacySigningMDs" option in the `etc/pki/tls/legacy-settings` policy configuration file, for example: echo 'LegacySigningMDs md5' >> /etc/pki/tls/legacy-settings You can also enable the MD5 verification by setting the "OPENSSL_ENABLE_MD5_VERIFY" environment variable.	Story Points:	---
Clone Of:
Clones:	1335915 (view as bug list)		Environment:
Last Closed:	2017-03-21 10:11:27 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	1335911, 1343211

Description Nikos Mavrogiannopoulos 2016-05-13 14:22:41 UTC

RHEL includes several cryptographic components who's security doesn't remain constant over time. Algorithms such as (cryptographic) hashing and encryption typically have a lifetime after which they are considered either too risky to use or plain insecure. That would mean we need to phase out such algorithms from the default settings, or completely disable if they could cause irreparable issue. 

This bug is about disabling the MD5 algorithm from the OpenSSL library, while at the same hand providing a configuration method for MD5 to be allowed when needed.

For future extensibility in RHEL-7 it is recommended for any introduced configuration method to be re-usable for future algorithm or parameter deprecation (e.g., SHA1 or less than 1024-bit RSA/DH parameters), and ideally part of upstream.

Comment 2 Tomas Mraz 2016-10-05 09:26:40 UTC

I've found that it was possible to verify also certificates using MD2, MD4, and SHA0, I've disabled these together with MD5.

The system administrator can re-enable some of them with

echo 'LegacySigningMDs md5 md4' >> /etc/pki/tls/legacy-settings

For MD5 it is also possible to enable it by setting environment variable OPENSSL_ENABLE_MD5_VERIFY to any value (same method as in RHEL-7).

Comment 10 errata-xmlrpc 2017-03-21 10:11:27 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2017-0660.html

Comment 11 BK 2019-11-20 17:34:24 UTC

Hi,

The option to enable MD4 in legacy does not work when fips is enabled. Any workaround for that?
I am trying to connect to exchange which uses NTLM protocol and NTLM protocol uses MD4 and using fips is compliance.

So I need to allow md4 hashing and at the same time enable fips as we well. I am using redhat7.

Thanks,
BK

Comment 12 Tomas Mraz 2019-11-20 17:39:46 UTC

The legacy algorithms handling for signature verification is completely unrelated to the general disablement of MD4 in FIPS mode. There is a way how to use MD4 from openssl in FIPS mode but that requires the application to use a specific API call from openssl to mark the MD4 use as non-security relevant. There is no way around that from system administrator side.

Comment 13 BK 2019-11-20 18:07:26 UTC

Thank you Tomas. Could you please direct me to the specific API call from openssl. 
I was not able to find it.
Even this does not work ... openssl dgst -non-fips-allow -md4 <<fielname>>

I will open this up with openssl as well, but if you have anything handy that would be a huge help.

Thanks,
BK

Comment 14 Tomas Mraz 2019-11-21 11:59:01 UTC

This is an API call, not a command line option.

Comment 15 BK 2019-11-21 14:51:27 UTC

I understand. Could you please let me know the API from openssl.

Thanks,
BK