Terrapin Attack
terrapin-attack.com
  • s38b35M5@lemmy.worldEnglish
    12·
    2 years ago

    I can’t believe its already been almost thirty years since SSH was created! Time to further harden your servers and clients by removing (now) insecure KEX algos.

    • rammer@sopuli.xyz
      3·
      2 years ago

      Please note that if you do this then some older devices will stop working. (cough Cisco cough)

  • Grass@sh.itjust.works
    3·
    2 years ago

    I was worried I would have to ask for a tl;dr for dummies like I’m 5, but everything is categorized nicely under questions one may have on the topic. It’s been a while since I’ve been able to get meaningful information from a website without a huge commitment.

    • paroxon
      1·
      2 years ago

      In short: no. Any piece of software that implements SSH (library (e.g. python’s paramiko), client application (e.g. PuTTy), server application (e.g. OpenSSH Server), etc.) is potentially vulnerable.

      In medium: It affects any application or library that implements the SSH protocol and offers either the ChaCha20-poly1305 encryption algorithm, or a chained block cipher (CBC) encryption algorithm paired with a MAC algorithm that uses Encrypt then MAC (EtM). An example of the latter would be a connection using aes256-cbc as the encryption algorithm combined with the hmac-sha2-256-etm@openssh.com mac algorithm.

      If you’re using OpenSSH, you can see the list of available encryption and mac algorithms with ssh -Q ciphers and ssh -Q mac respectively.

      Sample output:

      $ ssh -Q cipher
3des-cbc
aes128-cbc
aes192-cbc
aes256-cbc
aes128-ctr
aes192-ctr
aes256-ctr
aes128-gcm@openssh.com
aes256-gcm@openssh.com
chacha20-poly1305@openssh.com

$ ssh -Q mac
hmac-sha1
hmac-sha1-96
hmac-sha2-256
hmac-sha2-512
hmac-md5
hmac-md5-96
umac-64@openssh.com
umac-128@openssh.com
hmac-sha1-etm@openssh.com
hmac-sha1-96-etm@openssh.com
hmac-sha2-256-etm@openssh.com
hmac-sha2-512-etm@openssh.com
hmac-md5-etm@openssh.com
hmac-md5-96-etm@openssh.com
umac-64-etm@openssh.com
umac-128-etm@openssh.com

      More info: There are 3 CVEs associated with Terrapin: the first, CVE-2023-48795, regards the general flaw in the SSH protocol.

      The other two (CVE-2023-46445 and CVE-2023-46446) are specifically for the AsyncSSH library which, due to implementation details, has additional vulnerabilities that can be exploited on top of those made available by CVE-2023-48795.