3 ms·

This is not sshd, this is a golang binary that uses the stdlib ssh lib. You would have to either a) figure out how to escape out of a golang binary, or b) if t

by qudat 2y ago

This is not sshd, this is a golang binary that uses the stdlib ssh lib. You would have to either a) figure out how to escape out of a golang binary, or b) if the go code executes shell commands with some user provided text, trying to shell inject something in there.

cwillu 2y ago
Or convince the ssh daemon to pass on terminal escape codes to another user. https://nvd.nist.gov/vuln/detail/CVE-2021-33477 https://nvd.nist.gov/vuln/detail/CVE-2021-33477
- deleted 2y ago
  [deleted]
- quackduck 2y ago
  whoa
- raggi 2y ago
  yup, not an extensive list, but further demonstrative: - terminal emulators are not security hardened clients against malicious actors - ssh lacks PKI and is inconvenient so users never do prekeying in practice, so it's TOFU / zero server assertion in most practical cases (i.e. easy to mitm) - ssh channel features are a constant concern, for server resources and for client features like agents, agents are easy to disable - most ssh implementations don't scale that well, it wasn't ever really a goal to do so - there are few tools for auditing and monitoring, unlike the common protocols/services/clients fun for toys, but i wouldn't put credit card details in there, unlike some streamers started doing lately.
  - cwillu 2y ago
    ssh definitely supports PKI, it's just not the standard workflow for individuals ssh-keygen (1): ssh-keygen supports signing of keys to produce certificates that may be used for user or host authentication. Certificates consist of a public key, some identity information, zero or more principal (user or host) names and a set of options that are signed by a Certification Authority (CA) key. Clients or servers may then trust only the CA key and verify its signature on a certificate rather than trusting many user/host keys. Note that OpenSSH certificates are a different, and much simpler, format to the X.509 certificates used in ssl(8)
    - raggi 2y ago
      I'm not talking about supporting public key cryptography, I'm talking about having a specific and usable deployment of a PKI. The closest thing SSH has is SSHFP, which depends on DNSSEC, which is according to many opinions, DOA.
    - password4321 2y ago
      TIL about PKIX-SSH, OpenSSH + X.509. https://gitlab.com/secsh/pkixssh https://gitlab.com/secsh/pkixssh http://tech.ciges.net/blog/openssh-with-x509-certificates-how-to/ http://tech.ciges.net/blog/openssh-with-x509-certificates-ho... Right now I'd stick with something like Gravitational Teleport (overkill); Warpgate may become the perfect fit for this niche soon. https://github.com/warp-tech/warpgate https://github.com/warp-tech/warpgate It's also worth knowing about SSH clients that can use X.509 certificate keys as normal pre-shared keys with any SSH server, like PuttyCAC and built-in for macOS High Sierra and later. https://www.idmanagement.gov/implement/scl-ssh/ https://www.idmanagement.gov/implement/scl-ssh/
      - zie 2y ago
        OpenBAO and Hashicorp Vault also have built-in support for SSH certs: https://openbao.org/docs/secrets/ssh/signed-ssh-certificates/ https://openbao.org/docs/secrets/ssh/signed-ssh-certificates...
    - anilakar 2y ago
      PKI, with I in bold quotation marks. While it supports serial numbers, expiration dates and key revocation lists, it does not allow certificate chaining. That means whoever signs keys for end users has implicit access to the master key.

by qudat 2y ago

cwillu 2y ago

Or convince the ssh daemon to pass on terminal escape codes to another user. https://nvd.nist.gov/vuln/detail/CVE-2021-33477 https://nvd.nist.gov/vuln/detail/CVE-2021-33477

deleted 2y ago
[deleted]
quackduck 2y ago
whoa
raggi 2y ago
yup, not an extensive list, but further demonstrative: - terminal emulators are not security hardened clients against malicious actors - ssh lacks PKI and is inconvenient so users never do prekeying in practice, so it's TOFU / zero server assertion in most practical cases (i.e. easy to mitm) - ssh channel features are a constant concern, for server resources and for client features like agents, agents are easy to disable - most ssh implementations don't scale that well, it wasn't ever really a goal to do so - there are few tools for auditing and monitoring, unlike the common protocols/services/clients fun for toys, but i wouldn't put credit card details in there, unlike some streamers started doing lately.
- cwillu 2y ago
  ssh definitely supports PKI, it's just not the standard workflow for individuals ssh-keygen (1): ssh-keygen supports signing of keys to produce certificates that may be used for user or host authentication. Certificates consist of a public key, some identity information, zero or more principal (user or host) names and a set of options that are signed by a Certification Authority (CA) key. Clients or servers may then trust only the CA key and verify its signature on a certificate rather than trusting many user/host keys. Note that OpenSSH certificates are a different, and much simpler, format to the X.509 certificates used in ssl(8)
  - raggi 2y ago
    I'm not talking about supporting public key cryptography, I'm talking about having a specific and usable deployment of a PKI. The closest thing SSH has is SSHFP, which depends on DNSSEC, which is according to many opinions, DOA.
  - password4321 2y ago
    TIL about PKIX-SSH, OpenSSH + X.509. https://gitlab.com/secsh/pkixssh https://gitlab.com/secsh/pkixssh http://tech.ciges.net/blog/openssh-with-x509-certificates-how-to/ http://tech.ciges.net/blog/openssh-with-x509-certificates-ho... Right now I'd stick with something like Gravitational Teleport (overkill); Warpgate may become the perfect fit for this niche soon. https://github.com/warp-tech/warpgate https://github.com/warp-tech/warpgate It's also worth knowing about SSH clients that can use X.509 certificate keys as normal pre-shared keys with any SSH server, like PuttyCAC and built-in for macOS High Sierra and later. https://www.idmanagement.gov/implement/scl-ssh/ https://www.idmanagement.gov/implement/scl-ssh/
    - zie 2y ago
      OpenBAO and Hashicorp Vault also have built-in support for SSH certs: https://openbao.org/docs/secrets/ssh/signed-ssh-certificates/ https://openbao.org/docs/secrets/ssh/signed-ssh-certificates...
  - anilakar 2y ago
    PKI, with I in bold quotation marks. While it supports serial numbers, expiration dates and key revocation lists, it does not allow certificate chaining. That means whoever signs keys for end users has implicit access to the master key.