'A critical bug that can leak secret cryptographic keys has just just
been fixed in OpenSSH, one of the more widely used implementations of
the secure shell (SSH) protocol.
The vulnerability resides only in the version end users use to connect
to servers and not in versions used by servers. A maliciously
configured server could exploit it to obtain the contents of the
connecting computer's memory, including the private encryption key
used for SSH connections. The bug is the result of code that enables
an experimental roaming feature in OpenSSH versions 5.4 to 7.1
"The matching server code has never been shipped, but the client code
was enabled by default and could be tricked by a malicious server into
leaking client memory to the server, including private client user
keys," OpenSSH officials wrote in an advisory published Thursday. "The
authentication of the server host key prevents exploitation by a
man-in-the-middle, so this information leak is restricted to
connections to malicious or compromised servers."
The advisory said that anyone using a vulnerable version should update
right away. Those who are unable to update should disable roaming by
adding the string UseRoaming no to the global ssh_config(5) file or to
the user configuration in ~/.ssh/config, or by entering -UseRoaming=no
on the command line.'
Dept. of Computer Science
University of Waikato, NZ
+64 (7) 858-5174