Bit of an alarmist headline here. The vulnerability has been patched in the most common clients (openssh) and it was because the protocol wasn’t being implemented correctly. To say that the SSH protocol “just got a lot weaker” is just not true.
It doesn’t look that simple to me. From the Terrapin paper:
Although we suggest backward-compatible countermea- sures to stop our attacks, we note that the security of the SSH protocol would benefit from a redesign from scratch. This redesign should be guided by all findings and insights from both practical and theoretical security analysis, in a similar manner as was done for TLS 1.3.
It seems the protocol itself needs a revision and implementation-specific patches are easier and less-than-ideal solutions.
One could argue that even these solutions they provide are already changes to the protocol, and not just fixes to implementation bugs. Both the Sequence Number Reset and Full Transcript Hash add or change functionality at the communication protocol level, rather than simply covering corner cases.
Yes I was wrong to say that this an implementation detail rather than a protocol problem as the OpenSSH release notes to prevent this vulnerability include extensions to the SSH Transport Protocol, however I still believe that the headline is sensationalist at best since it can and has been protected against by patching ssh clients and servers. It would be entirely unreasonable in the majority of cases to simply stop using SSH on the basis of this vulnerability and that’s why I think the headline exaggerates the problem. The Register has a much more measured take on this including comments from the paper’s authors that people shouldn’t panic and try to fix immediately.
Yeaaaa, a complete redesign from scratch sounds way more dangerous. “Noah, get the boat” isn’t always the best answer. There’s been a lot of thought and testing put into the magnificent work that is SSH over the past few decades.
TLS and SSH has quite different attack vectors so sure, basing SSH on TLS 1.3 would prevent the problems SSH has, but also bring in the problems TLS has. Thing is, I much prefer SSHs tradeof for things SSH is used for while TLS could be argued makes a lot more sense for the HTTPS use case. It just very different chains of trust with very different weak points, just pointing at TLS 1.3 as a solution when talking about SSH is quite ignorant.
[For Terrapin to be viable, the connection it interferes with also must be secured by either “ChaCha20-Poly1305” or “CBC with Encrypt-then-MAC,” both of which are cipher modes added to the SSH protocol (in 2013 and 2012, respectively
Well thats easy then, just change your allowed ciphers.
I like this internet turtle.
Turtles are such underrated creatures and most people don’t realise how important they are to computer science. Turtle robots! Turtle graphics! Not to even mention the very concept of shell access! And yes, turtles are probably very happy that Secure Shell was invented.
MitM attacks are also one of the major threats to MFA.
They don’t seem to talk much about TLS which is the current standard for most things (VoIP, email.) We still use ssh for a lot but HTTPS is secured through TLS 1.3
This is the best summary I could come up with:
Once in place, this piece of dedicated hardware surreptitiously inhaled thousands of user names and passwords before it was finally discovered.
Ylönen, who at the time knew little about implementing strong cryptography in code, set out to develop the Secure Shell Protocol (SSH) in early 1995, about three months after the discovery of the password sniffer.
As one of the first network tools to route traffic through an impregnable tunnel fortified with a still-esoteric feature known as “public key encryption,” SSH quickly caught on around the world.
Today, it’s hard to overstate the importance of the protocol, which underpins the security of apps used inside millions of organizations, including cloud environments crucial to Google, Amazon, Facebook, and other large companies.
Now, nearly 30 years later, researchers have devised an attack with the potential to undermine, if not cripple, cryptographic SSH protections that the networking world takes for granted.
The attack targets the BPP, short for Binary Packet Protocol, which is designed to ensure that adversaries with an active position can’t add or drop messages exchanged during the handshake.
The original article contains 658 words, the summary contains 178 words. Saved 73%. I’m a bot and I’m open source!
