Date: Sat, 17 Mar 2018 14:53:46 +0100 From: Salvatore Bonaccorso <carnil@...ian.org> To: oss-security@...ts.openwall.com Subject: Re: Squirrelmail directory traversal vulnerability allows exfiltrating files from server Hi On Sat, Mar 17, 2018 at 10:03:43AM +0100, Hanno Böck wrote: > Hi, > > During the Troopers conference this week an unpatched vulnerability in > squirrelmail was presented by Florian Grunow from ERNW . > > The issue is that when uploading a mail attachment a temporary file is > generated on the server that the client later references when sending > the mail. The filename is not sanitized in any way, so by passing a > filename of the form "../../../../some_path/some_filename" one can use > this to attach arbitrary files from the server that can be accessed by > the PHP process to a mail. Thus an attacker who has a mail account > could use this to exfiltrate files and send them as attachments. > > The bug is unfixed. The finders say they tried to reach out to the > squirrelmail developers, but were unable to contact them. > > Squirrelmail hasn't had a release for many years and the webpage has > its last news from 2013. But despite that until recently the subversion > repository and the provided svn snapshots still provided security > fixes, e.g. a 2017 found injection vuln  was fixed. > Despite its stale state I believe many people still use squirrelmail, > in my experience it works better than alternatives like roundcube in > situations where you have very weak internet connections. > > I created a preliminary quick and dirty patch that should close the > main hole . It guarantees that the filename only contains letters > and numbers (this should be okay as the filename is created by > squirrelmail and usually doesn't contain any user-controlled > characters in normal operation) and otherwise just terminates the > process. There may be an obscure cornercase where this patch does not > fully protect: If for some reason a user can guess another users > temporary filename while writing a mail one may be able to exfiltrate > that. I find that unlikely enough that I haven't bothered looking more > into this. > > The researchers found this flaw while investigating a check point > appliance that bundles squirrelmail for their webmail functionality. As > squirrelmail is GPL I asked check point to share the patch, which they > did and I'm providing it here . I haven't reviewed it, but the ERNW > people told me it may not work with all PHP versions. > > In any case if anyone has contact to the squirrelmail authors it would > be great if they could incorporate a fix (and maybe even provide a new > release). Otherwise everyone using squirrelmail should obviously > patch this manually. MITRE has assigned 'CVE-2018-8741' for this issue. Regards, Salvatore
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