69

I'd like to ask if there's a way to lower SSL security level to 1 on Ubuntu 20.04, since I'm receiving:

141A318A:SSL routines:tls_process_ske_dhe:dh key too small

when trying to curl the website.

Curl works if I add --ciphers 'DEFAULT:!DH' parameter, however, I am not able to fetch a website via my client app written in C#. The website also works when opened via browser.

According to bugs.launchpad.net the Ubuntu team set higher SSL security level on purpose.

In several places I came across an information that changing CipherString = DEFAULT@SECLEVEL=2 to 1 in openssl.cnf helps, but my config file did not have such a line at all and adding it had no effect.

I do not control the website server, so I am not able to change its security configuration.

Any ideas? Would installing some older openSSL package help?

Thanks in advance

EDIT: As for changes to my config file, I've added the following at the end:

system_default = system_default_sect 

[system_default_sect] 
MinProtocol = TLSv1.2
CipherString = DEFAULT@SECLEVEL=1 

Output from openssl version -a:

OpenSSL 1.1.1f 31 Mar 2020 built on: Mon Apr 20 11:53:50 2020 UTC
platform: debian-amd64
options: bn(64,64) rc4(16x,int) des(int) blowfish(ptr)
compiler: gcc -fPIC -pthread -m64 -Wa,--noexecstack -Wall -Wa,
--noexecstack -g -O2 -fdebug-prefix-map=/build/openssl-P_ODHM/openssl-1.1.1f=. 
-fstack-protector-strong -Wformat -Werror=format-security
-DOPENSSL_TLS_SECURITY_LEVEL=2 -DOPENSSL_USE_NODELETE
-DL_ENDIAN -DOPENSSL_PIC -DOPENSSL_CPUID_OBJ
-DOPENSSL_IA32_SSE2 -DOPENSSL_BN_ASM_MONT
-DOPENSSL_BN_ASM_MONT5 -DOPENSSL_BN_ASM_GF2m
-DSHA1_ASM -DSHA256_ASM -DSHA512_ASM -DKECCAK1600_ASM
-DRC4_ASM -DMD5_ASM -DAESNI_ASM -DVPAES_ASM -DGHASH_ASM
-DECP_NISTZ256_ASM -DX25519_ASM -DPOLY1305_ASM -DNDEBUG
-Wdate-time -D_FORTIFY_SOURCE=2
OPENSSLDIR: "/usr/lib/ssl" ENGINESDIR:
"/usr/lib/x86_64-linux-gnu/engines-1.1" Seeding source: os-specific
  • Is your C# application calling OpenSSL APIs directly? I'm not familiar with the C# OpenSSL bindings, but in C you can change the security level using SSL_CTX_set_cipher_list(ctx, "DEFAULT:@SECLEVEL=1");. Or alternatively SSL_CTX_set_security_level(ctx, 1). – Matt Caswell Apr 30 '20 at 08:09
  • Unfortunately I use a high-level class to do HTTP requests. But would it be possible to call this function from C to change security level for the whole system? – Łukasz Sypniewski Apr 30 '20 at 08:56
  • Calling it in C will only change the setting for the current process – Matt Caswell Apr 30 '20 at 09:36
  • Can you show what changes you made to your config file, and also the output from openssl version -a? – Matt Caswell Apr 30 '20 at 09:38
  • @MattCaswell I added the information you asked for to the question – Łukasz Sypniewski Apr 30 '20 at 11:37

5 Answers5

107

You don't have your config changes quite right. You need to add this to the beginning of your config file:

openssl_conf = default_conf

And then this to the end:

[ default_conf ]

ssl_conf = ssl_sect

[ssl_sect]

system_default = system_default_sect

[system_default_sect] MinProtocol = TLSv1.2 CipherString = DEFAULT:@SECLEVEL=1

Note that if you prefer you can make changes to a local copy of the config file, and then ensure your process is started with the environment variable OPENSSL_CONF defined to point at the location of your config file:

export OPENSSL_CONF=/path/to/my/openssl.cnf

This way you can make changes without having to impact your entire system.

Note: To find the system's openssl.cnf file, run the following:

% openssl version -d

the run ls -l on the directory outputted to see where the openssl.cnf file is via its symlink in that directory as needed.

baptx
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Matt Caswell
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  • Thanks! That fixed it for me. After upgrading from Ubuntu 18.04 LTS to 20.04 LTS my wget refused to connect to a server I had previously copied files from. With this modification of openssl.cnf it works again. – Norbert S May 30 '20 at 01:42
  • I did the updates to the openssl.cnf but still the same issue.. even after rebooting the system – johnny Jun 27 '20 at 17:45
  • Thanks, this had me stumped, the server I was having an issue with is rated A on SSL Labs, surely this is a bug? – Caleb Jun 29 '20 at 11:06
  • @Caleb good question, maybe it is not considered a security vulnerability but just a security that can be improved? – baptx Aug 06 '20 at 18:10
  • 1
    @johnny it is not working for me either, did anyone get this solution working on Ubuntu 20.04? At least I found a workaround by using the curl command in a Debian LXC container where I just need to change SECLEVEL=2 to SECLEVEL=1. Update: I shared an answer that works by using the Debian config file on Ubuntu. Update 2: in fact this solution seems to work if you extract the default configuration from the deb file by downloading it on https://packages.ubuntu.com/search?keywords=openssl&searchon=names. – baptx Aug 06 '20 at 18:51
  • 1
    @johnny In fact the answer did not work for me because I had a wrong config file using [system_default_sect] instead of [ssl_default_sect]. It seems to be an error that I copy-pasted from https://wiki.debian.org/ContinuousIntegration/TriagingTips/openssl-1.1.1. I think it is better to use the system_default_sect name to be consistent with Debian. By the way, there seems to be an unnecessary colon in DEFAULT:@SECLEVEL=1 which is not present in the Debian config file. – baptx Aug 06 '20 at 19:47
  • It works for me! I have clear setup of ubuntu 20.04 LTS. Thanks! – Costas Bakoulias Mar 04 '21 at 16:20
  • I think you need to restart the service like php-fpm. – Pardeep Poria Sep 10 '21 at 07:16
  • Two remarks, one this also works for fedora, and likely other distributions. However openssl version -d may not return the system openssl binary, because it depends on the PATH and as such this command return a different install (and config). – bric3 Mar 19 '22 at 23:11
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    After upgrade to 22.04 this solution does not work for me anymore. – nobody Aug 12 '22 at 10:28
20

Edit openssl.conf file:

sudo nano /etc/ssl/openssl.cnf

Add this line at the top:

openssl_conf = openssl_init

And add these lines at the end:

[openssl_init]
ssl_conf = ssl_sect

[ssl_sect] system_default = system_default_sect

[system_default_sect] CipherString = DEFAULT@SECLEVEL=1

It works for me. :)

Ref: When I try to CURL a website I get SSL error

For the Laravel, also run

sudo service php7.4-fpm restart
WHY
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  • Thank you!!!! 3 days of searching ODBC driver 17 SQL issues with server 2012 r2 led me here and you fixed it!! – Top-Bot Mar 22 '21 at 15:29
5

The two solutions above were confusing for me.

You just need two blocks of modifications in /usr/lib/ssl/openssl.cnf as documented with this diff:

     rcsdiff ./openssl.cnf 
    ===================================================================
    RCS file: ./openssl.cnf,v
    retrieving revision 1.1
    diff -r1.1 ./openssl.cnf
    13a14,15
    > openssl_conf = default_conf
    > 
    350a353,362
    > 
    > [default_conf]
    > ssl_conf = ssl_sect
    > 
    > [ssl_sect]
    > system_default = system_default_sect
    > 
    > [system_default_sect]
    > MinProtocol = TLSv1.2
    > CipherString = DEFAULT@SECLEVEL=1

For cut&paste:

openssl_conf = default_conf
[default_conf]
ssl_conf = ssl_sect

[ssl_sect] system_default = system_default_sect

[system_default_sect] MinProtocol = TLSv1.2 CipherString = DEFAULT@SECLEVEL=1

4

Update: the previous answer seems to work if you extract the default configuration from the deb file by downloading it on https://packages.ubuntu.com/search?keywords=openssl&searchon=names.

Update 2: in fact the previous answer did not work for me because I had a wrong config file using [system_default_sect] instead of [ssl_default_sect]. It seems to be an error that I copy-pasted from https://wiki.debian.org/ContinuousIntegration/TriagingTips/openssl-1.1.1. It is possible to use the name system_default_sect to be consistent with Debian, you just need to use it everywhere instead of ssl_default_sect.

Original answer:

The previous answer was not working for me on Ubuntu 20.04 so I used the config file from my Debian LXC container on Ubuntu and changed SECLEVEL=2 to SECLEVEL=1.

I saved the file as /etc/ssl/openssl_custom.cnf and then used the command shared in the previous answer to load another config file when you need to:

export OPENSSL_CONF=/etc/ssl/openssl_custom.cnf

Here is the full config file that worked for me (you can also extract the default configuration from the deb file by downloading it on https://packages.debian.org/stable/openssl):

#
# OpenSSL example configuration file.
# This is mostly being used for generation of certificate requests.
#

Note that you can include other files from the main configuration

file using the .include directive.

#.include filename

This definition stops the following lines choking if HOME isn't

defined.

HOME = .

Extra OBJECT IDENTIFIER info:

#oid_file = $ENV::HOME/.oid oid_section = new_oids

System default

openssl_conf = default_conf

To use this configuration file with the "-extfile" option of the

"openssl x509" utility, name here the section containing the

X.509v3 extensions to use:

extensions =

(Alternatively, use a configuration file that has only

X.509v3 extensions in its main [= default] section.)

[ new_oids ]

We can add new OIDs in here for use by 'ca', 'req' and 'ts'.

Add a simple OID like this:

testoid1=1.2.3.4

Or use config file substitution like this:

testoid2=${testoid1}.5.6

Policies used by the TSA examples.

tsa_policy1 = 1.2.3.4.1 tsa_policy2 = 1.2.3.4.5.6 tsa_policy3 = 1.2.3.4.5.7

#################################################################### [ ca ] default_ca = CA_default # The default ca section

#################################################################### [ CA_default ]

dir = ./demoCA # Where everything is kept certs = $dir/certs # Where the issued certs are kept crl_dir = $dir/crl # Where the issued crl are kept database = $dir/index.txt # database index file. #unique_subject = no # Set to 'no' to allow creation of # several certs with same subject. new_certs_dir = $dir/newcerts # default place for new certs.

certificate = $dir/cacert.pem # The CA certificate serial = $dir/serial # The current serial number crlnumber = $dir/crlnumber # the current crl number # must be commented out to leave a V1 CRL crl = $dir/crl.pem # The current CRL private_key = $dir/private/cakey.pem# The private key

x509_extensions = usr_cert # The extensions to add to the cert

Comment out the following two lines for the "traditional"

(and highly broken) format.

name_opt = ca_default # Subject Name options cert_opt = ca_default # Certificate field options

Extension copying option: use with caution.

copy_extensions = copy

Extensions to add to a CRL. Note: Netscape communicator chokes on V2 CRLs

so this is commented out by default to leave a V1 CRL.

crlnumber must also be commented out to leave a V1 CRL.

crl_extensions = crl_ext

default_days = 365 # how long to certify for default_crl_days= 30 # how long before next CRL default_md = default # use public key default MD preserve = no # keep passed DN ordering

A few difference way of specifying how similar the request should look

For type CA, the listed attributes must be the same, and the optional

and supplied fields are just that :-)

policy = policy_match

For the CA policy

[ policy_match ] countryName = match stateOrProvinceName = match organizationName = match organizationalUnitName = optional commonName = supplied emailAddress = optional

For the 'anything' policy

At this point in time, you must list all acceptable 'object'

types.

[ policy_anything ] countryName = optional stateOrProvinceName = optional localityName = optional organizationName = optional organizationalUnitName = optional commonName = supplied emailAddress = optional

#################################################################### [ req ] default_bits = 2048 default_keyfile = privkey.pem distinguished_name = req_distinguished_name attributes = req_attributes x509_extensions = v3_ca # The extensions to add to the self signed cert

Passwords for private keys if not present they will be prompted for

input_password = secret

output_password = secret

This sets a mask for permitted string types. There are several options.

default: PrintableString, T61String, BMPString.

pkix : PrintableString, BMPString (PKIX recommendation before 2004)

utf8only: only UTF8Strings (PKIX recommendation after 2004).

nombstr : PrintableString, T61String (no BMPStrings or UTF8Strings).

MASK:XXXX a literal mask value.

WARNING: ancient versions of Netscape crash on BMPStrings or UTF8Strings.

string_mask = utf8only

req_extensions = v3_req # The extensions to add to a certificate request

[ req_distinguished_name ] countryName = Country Name (2 letter code) countryName_default = AU countryName_min = 2 countryName_max = 2

stateOrProvinceName = State or Province Name (full name) stateOrProvinceName_default = Some-State

localityName = Locality Name (eg, city)

0.organizationName = Organization Name (eg, company) 0.organizationName_default = Internet Widgits Pty Ltd

we can do this but it is not needed normally :-)

#1.organizationName = Second Organization Name (eg, company) #1.organizationName_default = World Wide Web Pty Ltd

organizationalUnitName = Organizational Unit Name (eg, section) #organizationalUnitName_default =

commonName = Common Name (e.g. server FQDN or YOUR name) commonName_max = 64

emailAddress = Email Address emailAddress_max = 64

SET-ex3 = SET extension number 3

[ req_attributes ] challengePassword = A challenge password challengePassword_min = 4 challengePassword_max = 20

unstructuredName = An optional company name

[ usr_cert ]

These extensions are added when 'ca' signs a request.

This goes against PKIX guidelines but some CAs do it and some software

requires this to avoid interpreting an end user certificate as a CA.

basicConstraints=CA:FALSE

Here are some examples of the usage of nsCertType. If it is omitted

the certificate can be used for anything except object signing.

This is OK for an SSL server.

nsCertType = server

For an object signing certificate this would be used.

nsCertType = objsign

For normal client use this is typical

nsCertType = client, email

and for everything including object signing:

nsCertType = client, email, objsign

This is typical in keyUsage for a client certificate.

keyUsage = nonRepudiation, digitalSignature, keyEncipherment

This will be displayed in Netscape's comment listbox.

nsComment = "OpenSSL Generated Certificate"

PKIX recommendations harmless if included in all certificates.

subjectKeyIdentifier=hash authorityKeyIdentifier=keyid,issuer

This stuff is for subjectAltName and issuerAltname.

Import the email address.

subjectAltName=email:copy

An alternative to produce certificates that aren't

deprecated according to PKIX.

subjectAltName=email:move

Copy subject details

issuerAltName=issuer:copy

#nsCaRevocationUrl = http://www.domain.dom/ca-crl.pem #nsBaseUrl #nsRevocationUrl #nsRenewalUrl #nsCaPolicyUrl #nsSslServerName

This is required for TSA certificates.

extendedKeyUsage = critical,timeStamping

[ v3_req ]

Extensions to add to a certificate request

basicConstraints = CA:FALSE keyUsage = nonRepudiation, digitalSignature, keyEncipherment

[ v3_ca ]

Extensions for a typical CA

PKIX recommendation.

subjectKeyIdentifier=hash

authorityKeyIdentifier=keyid:always,issuer

basicConstraints = critical,CA:true

Key usage: this is typical for a CA certificate. However since it will

prevent it being used as an test self-signed certificate it is best

left out by default.

keyUsage = cRLSign, keyCertSign

Some might want this also

nsCertType = sslCA, emailCA

Include email address in subject alt name: another PKIX recommendation

subjectAltName=email:copy

Copy issuer details

issuerAltName=issuer:copy

DER hex encoding of an extension: beware experts only!

obj=DER:02:03

Where 'obj' is a standard or added object

You can even override a supported extension:

basicConstraints= critical, DER:30:03:01:01:FF

[ crl_ext ]

CRL extensions.

Only issuerAltName and authorityKeyIdentifier make any sense in a CRL.

issuerAltName=issuer:copy

authorityKeyIdentifier=keyid:always

[ proxy_cert_ext ]

These extensions should be added when creating a proxy certificate

This goes against PKIX guidelines but some CAs do it and some software

requires this to avoid interpreting an end user certificate as a CA.

basicConstraints=CA:FALSE

Here are some examples of the usage of nsCertType. If it is omitted

the certificate can be used for anything except object signing.

This is OK for an SSL server.

nsCertType = server

For an object signing certificate this would be used.

nsCertType = objsign

For normal client use this is typical

nsCertType = client, email

and for everything including object signing:

nsCertType = client, email, objsign

This is typical in keyUsage for a client certificate.

keyUsage = nonRepudiation, digitalSignature, keyEncipherment

This will be displayed in Netscape's comment listbox.

nsComment = "OpenSSL Generated Certificate"

PKIX recommendations harmless if included in all certificates.

subjectKeyIdentifier=hash authorityKeyIdentifier=keyid,issuer

This stuff is for subjectAltName and issuerAltname.

Import the email address.

subjectAltName=email:copy

An alternative to produce certificates that aren't

deprecated according to PKIX.

subjectAltName=email:move

Copy subject details

issuerAltName=issuer:copy

#nsCaRevocationUrl = http://www.domain.dom/ca-crl.pem #nsBaseUrl #nsRevocationUrl #nsRenewalUrl #nsCaPolicyUrl #nsSslServerName

This really needs to be in place for it to be a proxy certificate.

proxyCertInfo=critical,language:id-ppl-anyLanguage,pathlen:3,policy:foo

#################################################################### [ tsa ]

default_tsa = tsa_config1 # the default TSA section

[ tsa_config1 ]

These are used by the TSA reply generation only.

dir = ./demoCA # TSA root directory serial = $dir/tsaserial # The current serial number (mandatory) crypto_device = builtin # OpenSSL engine to use for signing signer_cert = $dir/tsacert.pem # The TSA signing certificate # (optional) certs = $dir/cacert.pem # Certificate chain to include in reply # (optional) signer_key = $dir/private/tsakey.pem # The TSA private key (optional) signer_digest = sha256 # Signing digest to use. (Optional) default_policy = tsa_policy1 # Policy if request did not specify it # (optional) other_policies = tsa_policy2, tsa_policy3 # acceptable policies (optional) digests = sha1, sha256, sha384, sha512 # Acceptable message digests (mandatory) accuracy = secs:1, millisecs:500, microsecs:100 # (optional) clock_precision_digits = 0 # number of digits after dot. (optional) ordering = yes # Is ordering defined for timestamps? # (optional, default: no) tsa_name = yes # Must the TSA name be included in the reply? # (optional, default: no) ess_cert_id_chain = no # Must the ESS cert id chain be included? # (optional, default: no) ess_cert_id_alg = sha1 # algorithm to compute certificate # identifier (optional, default: sha1) [default_conf] ssl_conf = ssl_sect

[ssl_sect] system_default = system_default_sect

[system_default_sect] MinProtocol = TLSv1.2 CipherString = DEFAULT@SECLEVEL=1

baptx
  • 477
0

For any system add at the top of openssl.cnf:

openssl_conf = default_conf

and at end of openssl.cnf:

  • For Debian add:

    [system_default_sect]
    MinProtocol = TLSv1.0
    CipherString = DEFAULT@SECLEVEL=2
    
  • For Ubuntu 20.04 add:

    [system_default_sect]
    MinProtocol = TLSv1    #important !
    CipherString = DEFAULT@SECLEVEL=2 # in my case works good with very old software