[jira] [Commented] (SSHD-925) See if SCP vulnerability CVE-2019-6111 applies and mitigate it if so

["Goldstein Lyor (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SSHD-925?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16870510#comment-16870510 ] 

Goldstein Lyor commented on SSHD-925:
-------------------------------------

When downloading a single file, it seems that the vulnerability does not exist since the client determines the local {{Path}} regardless of the name reported reported by the server when data is actually received. In this context, perhaps we should add a (configurable) validity check that the name reported by the server matches the one requested by the client. Note though that such a check is not trivial - e.g., do we check only the file name or the entire relative path ?

> See if SCP vulnerability CVE-2019-6111 applies and mitigate it if so
> --------------------------------------------------------------------
>
>                 Key: SSHD-925
>                 URL: https://issues.apache.org/jira/browse/SSHD-925
>             Project: MINA SSHD
>          Issue Type: Improvement
>    Affects Versions: 2.2.0
>            Reporter: Goldstein Lyor
>            Assignee: Goldstein Lyor
>            Priority: Major
>              Labels: scp, security-issue
>
> From [OpenSSH version 8.0 release notes|https://www.openssh.com/txt/release-8.0]
> {quote}
> This release contains mitigation for a weakness in the scp(1) tool and protocol (CVE-2019-6111): when copying files from a remote system to a local directory, scp(1) did not verify that the filenames that the server sent matched those requested by the client. This could allow a hostile server to create or clobber unexpected local files with attacker-controlled content.
> {quote}
> If indeed this vulnerability exists then also note the following
> {quote}
> The scp protocol relies on the remote shell for wildcard expansion, so there is no infallible way for the client's wildcard matching to perfectly reflect the server's. If there is a difference between client and server wildcard expansion, the client may refuse files from the server. For this reason, we have provided a new "-T" flag to scp that disables these client-side checks at the risk of reintroducing the attack described above.
> {quote}



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