pfSense weak DH vuln found with Kali

pooperman

hi all,
I set up pfSense and I was checking for general vulnerabilities.
Kali gave me luckily just one.

I have already changed the DH parameters as per:
link text

and created a new cert auth. and new certs.

any idea what is pending to get rid of the kali msg?

*kali laptop is connected to lan

pooperman

May I ask, if my question is just too complicated?

NogBadTheBad

Might help if you mention what version of pfSense your running.

https://nmap.org/nsedoc/

Exploits CVE-2014-3704 also known as 'Drupageddon' in Drupal. Versions < 7.32 of Drupal core are known to be affected.

stephenw10

Yeah I assumed that was the previous test which failed to run.

What key length did you generate the new key at?

Do you see that certs being used in a browser?

Steve

pooperman

latest version of pfSense. Just set this up a week ago.

new DH is 40xx bits

johnpoz

Not sure what your running... I don't recall tweaking any of my httpd settings on pfsense... I can fire one up out of the box on vm and scan again with ssltest..

But have no idea where your seeing dh that low

 Testing 370 ciphers via OpenSSL plus sockets against the server, ordered by encryption strength 

Hexcode  Cipher Suite Name (OpenSSL)       KeyExch.   Encryption  Bits     Cipher Suite Name (IANA/RFC)
-----------------------------------------------------------------------------------------------------------------------------
 xc030   ECDHE-RSA-AES256-GCM-SHA384       ECDH 256   AESGCM      256      TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384              
 xc028   ECDHE-RSA-AES256-SHA384           ECDH 256   AES         256      TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384              
 xc014   ECDHE-RSA-AES256-SHA              ECDH 256   AES         256      TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA                 
 x9f     DHE-RSA-AES256-GCM-SHA384         DH 4096    AESGCM      256      TLS_DHE_RSA_WITH_AES_256_GCM_SHA384                
 x6b     DHE-RSA-AES256-SHA256             DH 4096    AES         256      TLS_DHE_RSA_WITH_AES_256_CBC_SHA256                
 x39     DHE-RSA-AES256-SHA                DH 4096    AES         256      TLS_DHE_RSA_WITH_AES_256_CBC_SHA                   
 xc02f   ECDHE-RSA-AES128-GCM-SHA256       ECDH 256   AESGCM      128      TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256              
 x9e     DHE-RSA-AES128-GCM-SHA256         DH 4096    AESGCM      128      TLS_DHE_RSA_WITH_AES_128_GCM_SHA256

Just ran ssltest against pfsense and only see the cipers that do dh all at 4096

Only thing that comes back with possible vuln is

LUCKY13 (CVE-2013-0169), experimental     potentially VULNERABLE, uses cipher block chaining (CBC) ciphers with TLS. Check patches

NogBadTheBad

mac-pro:~ andy$ nmap --script ssl-dh-params.nse 172.16.0.1

Starting Nmap 7.40 ( https://nmap.org ) at 2019-03-25 18:49 GMT
Nmap scan report for pfsense (172.16.0.1)
Host is up (0.0019s latency).
Not shown: 995 filtered ports
PORT     STATE SERVICE
22/tcp   open  ssh
53/tcp   open  domain
443/tcp  open  https
8081/tcp open  blackice-icecap
8443/tcp open  https-alt
| ssl-dh-params: 
|   VULNERABLE:
|   Diffie-Hellman Key Exchange Insufficient Group Strength
|     State: VULNERABLE
|       Transport Layer Security (TLS) services that use Diffie-Hellman groups
|       of insufficient strength, especially those using one of a few commonly
|       shared groups, may be susceptible to passive eavesdropping attacks.
|     Check results:
|       WEAK DH GROUP 1
|             Cipher Suite: TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA
|             Modulus Type: Non-safe prime
|             Modulus Source: RFC5114/1024-bit DSA group with 160-bit prime order subgroup
|             Modulus Length: 1024
|             Generator Length: 1024
|             Public Key Length: 1024
|     References:
|_      https://weakdh.org

Nmap done: 1 IP address (1 host up) scanned in 5.73 seconds
mac-pro:~ andy$

Just looked at my certs in keychain, they're all 2048

johnpoz

I will fire up a clean vm...

 Testing robust (perfect) forward secrecy, (P)FS -- omitting Null Authentication/Encryption, 3DES, RC4 

 PFS is offered (OK)          ECDHE-RSA-AES256-GCM-SHA384 ECDHE-RSA-AES256-SHA384 ECDHE-RSA-AES256-SHA DHE-RSA-AES256-GCM-SHA384 DHE-RSA-AES256-SHA256
                              DHE-RSA-AES256-SHA ECDHE-RSA-AES128-GCM-SHA256 DHE-RSA-AES128-GCM-SHA256 
 Elliptic curves offered:     sect283k1 sect283r1 sect409k1 sect409r1 sect571k1 sect571r1 secp256k1 prime256v1 secp384r1 secp521r1 brainpoolP256r1 brainpoolP384r1 
                              brainpoolP512r1 
 DH group offered:            Unknown DH group (4096 bits)

What are you running on pfsense that listens on 8081?

NogBadTheBad

@johnpoz @BBcan177

Ah it's DNSBL.

Hmmm disable DNSBL and its a pass.

If I look at the cert and the key size is 2048.

Screenshot 2019-03-25 at 19.14.03.png

johnpoz

Key size is not the same has DH size... Sorry but out of the box the DH is 4096..

I just fired up a 2.4.4p1 clean VM... nothing more than clicking ok in the wizard and this is what the out of the box gui offers

 Testing 370 ciphers via OpenSSL plus sockets against the server, ordered by encryption strength 

Hexcode  Cipher Suite Name (OpenSSL)       KeyExch.   Encryption  Bits     Cipher Suite Name (IANA/RFC)
-----------------------------------------------------------------------------------------------------------------------------
 xc030   ECDHE-RSA-AES256-GCM-SHA384       ECDH 256   AESGCM      256      TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384              
 xc028   ECDHE-RSA-AES256-SHA384           ECDH 256   AES         256      TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384              
 xc014   ECDHE-RSA-AES256-SHA              ECDH 256   AES         256      TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA                 
 x9f     DHE-RSA-AES256-GCM-SHA384         DH 4096    AESGCM      256      TLS_DHE_RSA_WITH_AES_256_GCM_SHA384                
 x6b     DHE-RSA-AES256-SHA256             DH 4096    AES         256      TLS_DHE_RSA_WITH_AES_256_CBC_SHA256                
 x39     DHE-RSA-AES256-SHA                DH 4096    AES         256      TLS_DHE_RSA_WITH_AES_256_CBC_SHA                   
 xc02f   ECDHE-RSA-AES128-GCM-SHA256       ECDH 256   AESGCM      128      TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256              
 x9e     DHE-RSA-AES128-GCM-SHA256         DH 4096    AESGCM      128      TLS_DHE_RSA_WITH_AES_128_GCM_SHA256                


 Running client simulations (HTTP) via sockets 

 Android 4.2.2                No connection
 Android 4.4.2                TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)
 Android 5.0.0                TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256, 256 bit ECDH (P-256)
 Android 6.0                  TLSv1.2 ECDHE-RSA-AES128-GCM-SHA256, 256 bit ECDH (P-256)
 Android 7.0                  TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)
 Chrome 65 Win 7              TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)
 Chrome 70 Win 10             TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)
 Firefox 59 Win 7             TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)
 Firefox 62 Win 7             TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)
 IE 6 XP                      No connection
 IE 7 Vista                   No connection
 IE 8 Win 7                   No connection
 IE 8 XP                      No connection
 IE 11 Win 7                  TLSv1.2 DHE-RSA-AES256-GCM-SHA384, 4096 bit DH  (ffdhe4096)
 IE 11 Win 8.1                TLSv1.2 DHE-RSA-AES256-GCM-SHA384, 4096 bit DH  (ffdhe4096)
 IE 11 Win Phone 8.1          TLSv1.2 ECDHE-RSA-AES256-SHA, 256 bit ECDH (P-256)
 IE 11 Win 10                 TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)
 Edge 13 Win 10               TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)
 Edge 13 Win Phone 10         TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)
 Edge 15 Win 10               TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)
 Opera 17 Win 7               TLSv1.2 ECDHE-RSA-AES256-SHA, 256 bit ECDH (P-256)
 Safari 9 iOS 9               TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)
 Safari 9 OS X 10.11          TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)
 Safari 10 OS X 10.12         TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)
 Apple ATS 9 iOS 9            TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)
 Tor 17.0.9 Win 7             No connection
 Java 6u45                    No connection
 Java 7u25                    No connection
 Java 8u161                   TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)
 Java 9.0.4                   TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)
 OpenSSL 1.0.1l               TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)
 OpenSSL 1.0.2e               TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384, 256 bit ECDH (P-256)

So not sure what he is testing, but it sure isn't pfsense gui..

pooperman

DNSBL is also running on my pfsense

maybe kali checked the DNSBL cert?
@johnpoz thanks for rechecking!

NogBadTheBad

@pooperman is running pfblocker as well.

https://forum.netgate.com/topic/141220/pfblockerng-very-slow-at-dns

NogBadTheBad

@pooperman said in pfSense weak DH vuln found with Kali:

DNSBL is also running on my pfsense

maybe kali checked the DNSBL cert?
@johnpoz thanks for rechecking!

Yup stop DNSBL and you'll get a pass.

pooperman

just to get it right, DNSBL shall just redirect unwanted "data".
In order to keep integrity, it is using a cert and this cert is having insuffizient DH strength?

If so, according to my understanding there is actually no problem. In case someone breaks encryption it will just get all the rubbish that I do not want, correct?

johnpoz

@pooperman said in pfSense weak DH vuln found with Kali:

DNSBL

ask @BBcan177 maybe he can shed some light on what his package is doing... If its serving up something on https, then it should be using current best practices to do so..

pooperman

@johnpoz said in pfSense weak DH vuln found with Kali:

@pooperman said in pfSense weak DH vuln found with Kali:

DNSBL

ask @BBcan177 maybe he can shed some light on what his package is doing... If its serving up something on https, then it should be using current best practices to do so..

thanks for support!

will an @ and the name triggers something at the users interface in this forum ie. get an altert?
Or shall i contact him directly?

may I ask how and where you tested the DH key size (6th post)?

johnpoz

The @ should send him notification of this post.

The script I use to test ssl stuff is here
https://github.com/drwetter/testssl.sh

NogBadTheBad

He not been online for 11 days, I've made a post on reddit linking here.

BBcan177

@NogBadTheBad

The function that generates the cert is here:
https://github.com/pfsense/FreeBSD-ports/blob/devel/net/pfSense-pkg-pfBlockerNG-devel/files/usr/local/pkg/pfblockerng/pfblockerng.inc#L1024-L1049

I don't think its necessary for what the DNSBL server is serving, but you can change the settings in the code, delete the cert and then Force Update for the cert to be re-created with the new settings. If you test it successfully, let me know and I will change the code in the next release.

/var/unbound/dnsbl_cert.pem

johnpoz

Lets be clear is not the cert that the problem
https://docs.netgate.com/pfsense/en/latest/certificates/dh-parameters.html

What is pfblocker using that would be different than what the web gui is using?

We are not sure what they are actually hitting when they are testing.. All I can tell you is not the pfsense web gui.

So DNSBL listens on port what for SSL, you set this? 8443? How exactly does it serve this up where would it get its DH-parameters from? See the link above.

[2.4.4-RELEASE][admin@sg4860.local.lan]/etc: ls -la dh*
-rw-r--r--  1 root  wheel   245 Nov 17  2017 dh-parameters.1024
-rw-r--r--  1 root  wheel   424 Nov 17  2017 dh-parameters.2048
-rw-r--r--  1 root  wheel   595 Oct  4 08:37 dh-parameters.3072
-rw-r--r--  1 root  wheel   769 Nov 17  2017 dh-parameters.4096
-rw-r--r--  1 root  wheel  1115 Oct  4 08:37 dh-parameters.6144
-rw-r--r--  1 root  wheel  1464 Oct  4 08:37 dh-parameters.8192