scp File Create/Overwrite Vulnerability

A vulnerability exists in the 1.2.x releases of scp which, if properly exploited using a modified scp binary on the server end, can permit the remote server to spoof local pathnames and overwrite files belonging to the local user.

For example, following the command

scp user@remotehost:/somefile /home/user/newfile

the modified server on the remote machine maliciously sends the filename as ../../etc/passwd

the local user's scp program will then write the data to


(which is the same as /etc/passwd)

Note that the target file can only be overwritten if the local user has write access to it. As a result, it remains inadvisable to run scp as root.

This vulnerability applies to 1.2.x versions of ssh on the remote machine, irrespective of the version running as the client.

ssh-2.x on the remote employs a different protocol and as a result is reportedly not vulnerable to this bug.


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