Diffie Hellman vulnerability Logjam

Advisory ID CVE Number Date discovered Severity Advisory revision
STORM-2015-004 CVE-2015-4000 05/20/2015 medium v1

Vulnerability details

A vulnerability, named Logjam, has been discovered in TLS. It is related to the ability to downgrade the prime size used for the Diffie-Hellman key exchange against the TLS Protocol.

The combination of the Logjam attack on TLS and the known Diffie-Hellman weakness could lead to a widely available attack that may impact secure communications with a man-in-the-middle attack.

This security advisory only deals with the downgrade to DHE_EXPORT during a Diffie-Hellman negotiation in TLS.

Products

ProductSeverityDetail
Stormshield Network Security medium The product uses TLS in the webadmin, the authentication portal and the SSL proxy.
Stormshield Endpoint Security

None

The product acts as a TLS server and does not allow the use of export grade Diffie-Hellman.
Stormshield Data Security low The product could be configured to use weak Diffie-Hellman parameters.
Fast360

None

The product does not use Diffie-Hellman for TLS communications.
Netasq medium The product uses TLS in the webadmin, the authentication portal and the SSL proxy.

Revisions

Version Date Description
v1  05/21/2015 Initial release

 



Stormshield Network Security

CVSS Overall Score: 5.7      

Analysis

Impacted version

The webadmin, authentication portal and SSL proxy use TLS protocol to cipher data exchanges.

During the TLS handshake, the Diffie-Hellman algorithm may be used to establish a shared secret. However, the prime length used for that operation is not restricted and small primes (<=1024) may be chosen.

  • SNS v1.0 to v1.3.1
  • SNS v2.0.beta1 to v2.0.beta4

Workaround solution

Solution

For the Webadmin, the network admin can filter the access to allow connections from well known and safe networks.

For the SSL vpn portal, there is no workaround solution.

For the SSL proxy, there is no workaround solution.

The versions v1.4 and v2.0 (release) will fix this vulnerability.



Access vector Access complexity Authentication Confidentiality impact Integrity impact Availability impact
Network Medium None None Partial None
CVSS Base score: 4.3 CVSS Vector: (AV:N/AC:M/Au:N/C:N/I:P/A:N)
Exploitability Remediation Level Report Confidence
Proof of concept code Unavailable Confirmed
CVSS Temporal score: 3.9 CVSS Vector: (AV:N/AC:M/Au:N/C:N/I:P/A:N/E:POC/RL:U/RC:C)
Collateral Damage Potential Target Distribution
Low-Medium High [76-100%]
CVSS Environmental score: 5.7 CVSS Vector: (AV:N/AC:M/Au:N/C:N/I:P/A:N/E:POC/RL:U/RC:C/CDP:LM/TD:H)


Stormshield Data Security

CVSS Overall Score: 1.7      

Analysis

Impacted version

The Stormshield Data Authority Manager use Diffie-Hellman to exchange key to encrypt sensitive data:

  • Private Keys
  • Admin password

By default, the server uses the Group 5 so the Stormshield Data Authority Manager is not vulnerable. But the group could be configured in the “manager.ini” file with groups 1 or 2 (both vulnerable).

Starting from versions 9.1.1, the Diffie-Hellman groups 1, 2 and 5 corresponding to the key sizes 768, 1024 and 1536 bits have been replaced by the recommended groups 5, 14, 15, 16, 17 and 18 corresponding to the key sizes 1536, 2048, 3072, 4096, 6144 and 8192 bits.

  • Stormshield Data Authority Manager 8.0.0 and above
  • Stormshield Data Authority Manager 9.0.0 and above

Workaround solution

Solution

If using a vulnerable version, be sure to use Group 5 in the manager.ini, field “GroupDH” in “[Algo]” part.

Stormshield Data Authority Manager 9.1.1 fixes this vulnerability.



Access vector Access complexity Authentication Confidentiality impact Integrity impact Availability impact
Network Medium None None Partial None
CVSS Base score: 4.3 CVSS Vector: (AV:N/AC:M/Au:N/C:N/I:P/A:N)
Exploitability Remediation Level Report Confidence
Proof of concept code Official fix Confirmed
CVSS Temporal score: 3.4 CVSS Vector: (AV:N/AC:M/Au:N/C:N/I:P/A:N/E:POC/RL:OF/RC:C)
Collateral Damage Potential Target Distribution
High Low [0-25%]
CVSS Environmental score: 1.7 CVSS Vector: (AV:N/AC:M/Au:N/C:N/I:P/A:N/E:POC/RL:OF/RC:C/CDP:H/TD:L)


Netasq

CVSS Overall Score: 5.7      

Analysis

Impacted version

The webadmin, authentication portal and SSL proxy use TLS protocol to cipher data exchanges.

During the TLS handshake, the Diffie-Hellman algorithm may be used to establish a shared secret. However, the prime length used for that operation is not restricted and small primes (<=1024) may be chosen.

  • NETASQ v8.0.0 and above
  • NETASQ v9.0.0 and above
  • NETASQ v9.1.0 to v9.1.5.1

Workaround solution

Solution

For the Webadmin, the network admin can filter the access to allow connections from well known and safe networks.

For the SSL vpn portal, there is no workaround solution.

For the SSL proxy, there is no workaround solution.

No update is planned for v8.0, v8.1, v8.2 and v9.0 versions.

The v9.1.6 version will fix this issue.



Access vector Access complexity Authentication Confidentiality impact Integrity impact Availability impact
Network Medium None None Partial None
CVSS Base score: 4.3 CVSS Vector: (AV:N/AC:M/Au:N/C:N/I:P/A:N)
Exploitability Remediation Level Report Confidence
Proof of concept code Unavailable Confirmed
CVSS Temporal score: 3.9 CVSS Vector: (AV:N/AC:M/Au:N/C:N/I:P/A:N/E:POC/RL:U/RC:C)
Collateral Damage Potential Target Distribution
Low-Medium High [76-100%]
CVSS Environmental score: 5.7 CVSS Vector: (AV:N/AC:M/Au:N/C:N/I:P/A:N/E:POC/RL:U/RC:C/CDP:LM/TD:H)