Script`ssl-dh-params`

Script types:portrule
Categories:vuln,safe
Download:https://svn.nmap.org/nmap/scripts/ssl-dh-params.nse

Script Summary

Weak ephemeral Diffie-Hellman parameter detection for SSL/TLS services.

This script simulates SSL/TLS handshakes using ciphersuites that have ephemeralDiffie-Hellman as the key exchange algorithm.

Diffie-Hellman MODP group parameters are extracted and analyzed for vulnerabilityto Logjam (CVE 2015-4000) and other weaknesses.

Opportunistic STARTTLS sessions are established on services that support them.

Script Arguments

tls.servername: See the documentation for thetls library.
smbdomain,smbhash,smbnoguest,smbpassword,smbtype,smbusername: See the documentation for thesmbauth library.
mssql.domain,mssql.instance-all,mssql.instance-name,mssql.instance-port,mssql.password,mssql.protocol,mssql.scanned-ports-only,mssql.timeout,mssql.username: See the documentation for themssql library.
smtp.domain: See the documentation for thesmtp library.
randomseed,smbbasic,smbport,smbsign: See the documentation for thesmb library.
vulns.short,vulns.showall: See the documentation for thevulns library.

Example Usage

nmap --script ssl-dh-params <target>

Script Output

Host script results:| ssl-dh-params:|   VULNERABLE:|   Transport Layer Security (TLS) Protocol DHE_EXPORT Ciphers Downgrade MitM (Logjam)|     State: VULNERABLE|     IDs:  BID:74733  CVE:CVE-2015-4000|       The Transport Layer Security (TLS) protocol contains a flaw that is triggered|       when handling Diffie-Hellman key exchanges defined with the DHE_EXPORT cipher.|       This may allow a man-in-the-middle attacker to downgrade the security of a TLS|       session to 512-bit export-grade cryptography, which is significantly weaker,|       allowing the attacker to more easily break the encryption and monitor or tamper|       with the encrypted stream.|     Disclosure date: 2015-5-19|     Check results:|       EXPORT-GRADE DH GROUP 1|         Ciphersuite: TLS_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA|         Modulus Type: Non-safe prime|         Modulus Source: sun.security.provider/512-bit DSA group with 160-bit prime order subgroup|         Modulus Length: 512 bits|         Generator Length: 512 bits|         Public Key Length: 512 bits|     References:|       https://weakdh.org|       https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-4000|       https://www.securityfocus.com/bid/74733||   Diffie-Hellman Key Exchange Insufficient Diffie-Hellman Group Strength|     State: VULNERABLE|       Transport Layer Security (TLS) services that use Diffie-Hellman groups of|       insuffficient strength, especially those using one of a few commonly shared|       groups, may be susceptible to passive eavesdropping attacks.|     Check results:|       WEAK DH GROUP 1|         Ciphersuite: TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA|         Modulus Type: Safe prime|         Modulus Source: Unknown/Custom-generated|         Modulus Length: 512 bits|         Generator Length: 8 bits|         Public Key Length: 512 bits|     References:|       https://weakdh.org||   Diffie-Hellman Key Exchange Potentially Unsafe Group Parameters|     State: VULNERABLE|       This TLS service appears to be using a modulus that is not a safe prime and does|       not correspond to any well-known DSA group for Diffie-Hellman key exchange.|       These parameters MAY be secure if:|       - They were generated according to the procedure described in FIPS 186-4 for|         DSA Domain Parameter Generation, or|       - The generator g generates a subgroup of large prime order|       Additional testing may be required to verify the security of these parameters.|     Check results:|       NON-SAFE DH GROUP 1|         Cipher Suite: TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA|         Modulus Type: Non-safe prime|         Modulus Source: Unknown/Custom-generated|         Modulus Length: 1024 bits|         Generator Length: 1024 bits|         Public Key Length: 1024 bits|     References:|_      https://weakdh.org

Requires

Author:

Jacob Gajek

License: Same as Nmap--Seehttps://nmap.org/book/man-legal.html