The connection needs to slowly send data to the remote end for
stability. Additionally, the `exit` command should be issued when
closing the connction so it is reset back to the logon prompt.
AWS EC2 Nitro instances (and possibly others) support serial proxy
over SSH using the Instance Connect API:
https://docs.amazonaws.cn/en_us/AWSEC2/latest/UserGuide/
connect-to-serial-console.html
This process consists of sending an SSH pubkey to the serial proxy
control plane, connecting to a well-known URL with the instance ID
and port number as username, and the SSH private key as credential.
The resulting session is a "fragile" SSH context which does not
tolerate Channel-closing, requiring some special handling in Msf to
safeguard the initial Net::SSH::CommandStream.
Implement a BindAwsInstanceConnect Handler which loads an SSH key
from the local FS or generates a new one on the fly, passes the
pubkey to the InstanceConnect API, and then establishes SSH comms
with the InstanceConnect SSH proxy.
Implement a AwsInstanceConnectBind to handle resulting connetions,
derived from SshCommandShellBind, with an updated #bootstrap which
avoids meddling with the fragile CommandStream/Channel.
Testing:
Got serial console to the ttyS0 login prompt of a Nitro EC2 VM.
Logged in using previously-known credentials.
Verified console operations.
Notes:
Handler keeps firing, same as the SSM session concern.
There is a limit to the number of sessions which an instance can
hold (possibly only one).
RageLtMan