HTTPS SSL Certificate Signed using Weak Hashing Algorithm

ramkumar-n · ‎10-19-2011

I am support one client for, whom falls under Security scans mandatory for new implementation of ASA 5520 device . The client uses Nessus Scan and the test results are attached

The Nessus scanner hit on 1 Medium vulnerabilities, Could you pls review the statement and provide work around for the same.

Nessus Scanner reports

-----------------------------------

Medium Severity Vulnerability

Port : https (443/tcp)

Issue:

SSL Certificate Signed using Weak Hashing Algorithm

Synopsis :

The SSL certificate has been signed using a weak hash algorithm.

Description :

The remote service uses an SSL certificate that has been signed using

a cryptographically weak hashing algorithm - MD2, MD4, or MD5. These

signature algorithms are known to be vulnerable to collision attacks.

In theory, a determined attacker may be able to leverage this weakness

to generate another certificate with the same digital signature, which

could allow him to masquerade as the affected service.

See also :

http://tools.ietf.org/html/rfc3279

http://www.phreedom.org/research/rogue-ca/

http://www.microsoft.com/technet/security/advisory/961509.mspx

http://www.kb.cert.org/vuls/id/836068

Solution :

Contact the Certificate Authority to have the certificate reissued.

Plugin Output :

Here is the service's SSL certificate :

Subject Name:

Common Name: xxxxxxxxxx

Issuer Name:

Common Name: xxxxxxxxxx

Serial Number: D8 2E 56 4E

Version: 3

Signature Algorithm: MD5 With RSA Encryption

Not Valid Before: Aug 25 11:15:36 2011 GMT

Not Valid After: Aug 22 11:15:36 2021 GMT

Public Key Info:

Algorithm: RSA Encryption

Public Key: 00 AA AB 57 9C 74 FF E9 FB 68 E1 BF 69 90 8E D2 65 7F DF 40

D6 F6 29 E7 35 5E 16 FB 76 AA 03 3F 47 07 5A D0 6D 07 E0 EC

06 7E D4 9A 43 C6 B3 A6 93 B7 76 CC 58 31 25 36 98 04 30 E6

77 56 D7 C3 EE EF 7A 79 21 5E A0 78 9B F6 1B C5 E6 2A 10 B5

CB 90 3D 6D 7C A0 8D B1 B8 76 61 7F E2 D1 00 45 E2 A1 C7 9F

57 00 37 60 27 E1 56 2A 83 F5 0E 48 36 CC 61 85 59 54 0C CB

78 82 FB 50 17 CB 7D CD 15

Exponent: 01 00 01

Signature: 00 24 51 24 25 47 62 30 73 95 37 C4 71 7E BD E4 95 68 76 35

2E AF 2B 4A 23 EE 15 AF E9 09 93 3F 02 BB F8 45 00 A1 12 A9

F7 5A 0C E8 4D DB AE 92 70 E4 4C 24 10 58 6B A9 87 E1 F0 12

AE 12 18 E8 AB DF B9 02 F7 DA BE 3C 45 02 C4 1E 81 44 C2 74

25 A2 81 E7 D6 38 ED B9 66 4C 4A 17 AC E3 05 1A 01 14 88 23

E8 9F 3B 5C C5 B8 13 97 27 17 C3 02 5F 6E 7C DB 4C D3 65 B5

C5 FC 94 62 59 04 E7 7E FB

CVE :

CVE-2004-2761

BID :

BID 11849

BID 33065

Other References :

OSVDB:45106

OSVDB:45108

OSVDB:45127

CWE:310

Nessus Plugin ID :

35291

VulnDB ID:

69469

and try with configure the ssl encryption method with " ssl encryption 3des-sha1 aes128-sha1 aes256-sha1 rc4-md5" but it throws the same issue.

Here is ASA log

7|Oct 19 2011 01:59:34|725010: Device supports the following 4 cipher(s).

7|Oct 19 2011 01:59:34|725011: Cipher[1] : DES-CBC3-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[2] : AES128-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[3] : AES256-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[4] : RC4-MD5

7|Oct 19 2011 01:59:34|725008: SSL client production:xxxxxxxxx/2587 proposes the following 26 cipher(s).

7|Oct 19 2011 01:59:34|725011: Cipher[1] : ADH-AES256-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[2] : DHE-RSA-AES256-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[3] : DHE-DSS-AES256-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[4] : AES256-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[5] : ADH-AES128-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[6] : DHE-RSA-AES128-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[7] : DHE-DSS-AES128-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[8] : AES128-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[9] : ADH-DES-CBC3-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[10] : ADH-DES-CBC-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[11] : EXP-ADH-DES-CBC-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[12] : ADH-RC4-MD5

7|Oct 19 2011 01:59:34|725011: Cipher[13] : EXP-ADH-RC4-MD5

7|Oct 19 2011 01:59:34|725011: Cipher[14] : EDH-RSA-DES-CBC3-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[15] : EDH-RSA-DES-CBC-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[16] : EXP-EDH-RSA-DES-CBC-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[17] : EDH-DSS-DES-CBC3-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[18] : EDH-DSS-DES-CBC-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[19] : EXP-EDH-DSS-DES-CBC-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[20] : DES-CBC3-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[21] : DES-CBC-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[22] : EXP-DES-CBC-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[23] : EXP-RC2-CBC-MD5

7|Oct 19 2011 01:59:34|725011: Cipher[24] : RC4-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[25] : RC4-MD5

7|Oct 19 2011 01:59:34|725011: Cipher[26] : EXP-RC4-MD5

7|Oct 19 2011 01:59:34|725012: Device chooses cipher : DES-CBC3-SHA for the SSL session with client production:xxxxxxxx/2586

6|Oct 19 2011 01:59:34|725002: Device completed SSL handshake with client production:xxxxxxxxx/2586

6|Oct 19 2011 01:59:34|725007: SSL session with client production:xxxxxxxx/2586 terminated.

6|Oct 19 2011 01:59:34|302014: Teardown TCP connection 3201 for production:xxxxxxx/2586 to identity:xxxxxx/443 duration 0:00:00 bytes 758 TCP Reset-I

6|Oct 19 2011 01:59:34|302013: Built inbound TCP connection 3202 for production:xxxxxxxxxxx/2587 (xxxxxxxxx/2587) to identity:xxxxxx/443 (xxxxxxx/443)

6|Oct 19 2011 01:59:34|725001: Starting SSL handshake with client production:xxxxxxxxxxx/2587 for TLSv1 session.

7|Oct 19 2011 01:59:34|725010: Device supports the following 4 cipher(s).

7|Oct 19 2011 01:59:34|725011: Cipher[1] : DES-CBC3-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[2] : AES128-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[3] : AES256-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[4] : RC4-MD5

7|Oct 19 2011 01:59:34|725008: SSL client production:xxxxxxxxx/2587 proposes the following 26 cipher(s).

7|Oct 19 2011 01:59:34|725011: Cipher[1] : ADH-AES256-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[2] : DHE-RSA-AES256-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[3] : DHE-DSS-AES256-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[4] : AES256-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[5] : ADH-AES128-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[6] : DHE-RSA-AES128-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[7] : DHE-DSS-AES128-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[8] : AES128-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[9] : ADH-DES-CBC3-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[10] : ADH-DES-CBC-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[11] : EXP-ADH-DES-CBC-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[12] : ADH-RC4-MD5

7|Oct 19 2011 01:59:34|725011: Cipher[13] : EXP-ADH-RC4-MD5

7|Oct 19 2011 01:59:34|725011: Cipher[14] : EDH-RSA-DES-CBC3-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[15] : EDH-RSA-DES-CBC-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[16] : EXP-EDH-RSA-DES-CBC-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[17] : EDH-DSS-DES-CBC3-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[18] : EDH-DSS-DES-CBC-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[19] : EXP-EDH-DSS-DES-CBC-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[20] : DES-CBC3-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[21] : DES-CBC-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[22] : EXP-DES-CBC-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[23] : EXP-RC2-CBC-MD5

7|Oct 19 2011 01:59:34|725011: Cipher[24] : RC4-SHA

7|Oct 19 2011 01:59:34|725011: Cipher[25] : RC4-MD5

7|Oct 19 2011 01:59:34|725011: Cipher[26] : EXP-RC4-MD5

7|Oct 19 2011 01:59:34|725012: Device chooses cipher : DES-CBC3-SHA for the SSL session with client production:xxxxxxxxxx/2587

6|Oct 19 2011 01:59:34|725002: Device completed SSL handshake with client production:xxxxxxxxx/2587

H

mirober2 · ‎10-22-2011

Hi Ramkumar,

The report is complaining that the Certificate Authority who signed the ID certificate presented by the ASA used a weak hashing algorithm. First, you need to determine who signed the certificate.

If the certificate is self-signed by the ASA, you can generate a new certificate and use SHA1 as the hashing algorithm. To do this, the ASA needs to be running a software version that is at least 8.2(4) (8.3 and 8.4 software also support SHA1).

If the certificate is signed by an external CA, you need to contact them and ask them to sign a new certificate for you using SHA instead of MD5.

The links you posted have more information on this as well. Hope that helps.

-Mike

david.contreras · ‎12-09-2011

I am having this same issue with a PIX 8.0.4. How do I know if the cert is self signed?

I did try to do a sh crypto ca cert. Nothing came back. Does that mean it is not self signed?

Because this firewall has been running before I started working on it.

Let me know thanks,

David