4 ms·

DoS attack against Diffie-Hellman protocol

21 points by c0r0n3r 4y ago

c0r0n3r 4y ago
Who is affected? Websites, mail servers, and other Transport Layer Security (TLS) dependent services that support Diffie-Hellman key exchange using ephemeral keys (DHE cipher suites) are at risk of the DHEat attack. Services using other cryptographic protocols can also be affected. * Secure Shell (SSH) services support Diffie-Hellman key exchange methods. * Internet Protocol Security (IPsec) services offer DH groups. * OpenVPN servers support Diffie-Hellman key exchange in the control channel (DHE TLS ciphers).
josephcsible 4y ago
DHE has already been considered weak, with ECDHE as the recommended replacement, for a long time now, so I suspect that most systems operated by people who take security seriously already won't be vulnerable to this.
- meltyness 4y ago
  Your post corroborates SUSE[0] claims that ECDHE is not vulnerable to this. Default golang TLS server looks like it's got it's head on straight for this. [0] https://www.suse.com/support/kb/doc/?id=000020510 https://www.suse.com/support/kb/doc/?id=000020510
jslaD 4y ago
I’m getting a certificate error.
- LinuxBender 4y ago
  Qualys is too [1] [1] - https://www.ssllabs.com/ssltest/analyze.html?d=dheat-attack.com https://www.ssllabs.com/ssltest/analyze.html?d=dheat-attack....
- justinludwig 4y ago
  Looks like the URL for this post should be this instead: https://dheatattack.com/ https://dheatattack.com/
cft 4y ago
This is one year old (11/11/21), see date at the bottom: https://nvd.nist.gov/vuln/detail/CVE-2002-20001 https://nvd.nist.gov/vuln/detail/CVE-2002-20001
CodesInChaos 4y ago
I'm a bit confused what the attack is. Is it just that SSL handshakes are expensive for the server, while the client avoids the computational cost because it chooses a random public key instead of one for which it knows the private key? And why doesn't this also apply to plain RSA and ECDHE_RSA suites, which need to compute an expensive RSA private key operation, which should be similarly expensive as DH?

21 points by c0r0n3r 4y ago

Who is affected? Websites, mail servers, and other Transport Layer Security (TLS) dependent services that support Diffie-Hellman key exchange using ephemeral keys (DHE cipher suites) are at risk of the DHEat attack. Services using other cryptographic protocols can also be affected. * Secure Shell (SSH) services support Diffie-Hellman key exchange methods. * Internet Protocol Security (IPsec) services offer DH groups. * OpenVPN servers support Diffie-Hellman key exchange in the control channel (DHE TLS ciphers).

josephcsible 4y ago

DHE has already been considered weak, with ECDHE as the recommended replacement, for a long time now, so I suspect that most systems operated by people who take security seriously already won't be vulnerable to this.

meltyness 4y ago
Your post corroborates SUSE[0] claims that ECDHE is not vulnerable to this. Default golang TLS server looks like it's got it's head on straight for this. [0] https://www.suse.com/support/kb/doc/?id=000020510 https://www.suse.com/support/kb/doc/?id=000020510

jslaD 4y ago

I’m getting a certificate error.

LinuxBender 4y ago
Qualys is too [1] [1] - https://www.ssllabs.com/ssltest/analyze.html?d=dheat-attack.com https://www.ssllabs.com/ssltest/analyze.html?d=dheat-attack....
justinludwig 4y ago
Looks like the URL for this post should be this instead: https://dheatattack.com/ https://dheatattack.com/

cft 4y ago

This is one year old (11/11/21), see date at the bottom: https://nvd.nist.gov/vuln/detail/CVE-2002-20001 https://nvd.nist.gov/vuln/detail/CVE-2002-20001

CodesInChaos 4y ago

I'm a bit confused what the attack is. Is it just that SSL handshakes are expensive for the server, while the client avoids the computational cost because it chooses a random public key instead of one for which it knows the private key? And why doesn't this also apply to plain RSA and ECDHE_RSA suites, which need to compute an expensive RSA private key operation, which should be similarly expensive as DH?