oss-sec mailing list archives
Re: XSS security issue in gitweb for 'blob_plain' view with HTML files
From: Jakub Narebski <jnareb () gmail com>
Date: Fri, 3 Jun 2011 19:01:28 +0200
On Fri, 3 July 2011, Jamie Strandboge wrote:
https://launchpad.net/bugs/777804
[...]
---- I am reporting a persistent xss vector in gitweb, note this requires a user to have commit access to a repository that gitweb is configured to display. The vector is the fact that gitweb "serves" up xml files - which can (just as gitweb does) embed html that could be used to perform a cross-site scripting attack. e.g. (lol.xml). <?xml version="1.0" encoding="utf-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-US" lang="en-US"> <head> </head> <script>alert(1);</script> </html> and viewed at http://$HOSTNAME/$PATH_TO_GITWEB/?p=lolok;a=blob_plain;f=lol.xml ---- Thanks in advance for your cooperation in coordinating a fix for this issue,
In short: This is a feature, not a bug. Origin of current behavior: --------------------------- The 'blob_plain' action (raw view) together with support for path_info URLs were designed together so that gitweb could be used as a kind of deploy platform. For example you can browse git documentation from 'html' branch of git.git repository using gitweb, c.f. http://repo.or.cz/w/git.git/blob_plain/html:/git.html Also, by default (and I think in most configurations) there isn't anything worth stealing using cross-side scripting attack; there is no login information, no cookies with sensitive information... Proposal of solution: --------------------- Nevertheless gitweb include a germ of anti-XSS framework, namely $prevent_xss gitweb configuration variable. It is currently used to prevent displaying README.html from $GIT_DIR of repository, but I think it can be reused for this situation (at the cost of reduced feature set). Namely if $prevent_xss is true, we can simply serve all 'blob_plain' as either text/plain or application/octet-stream (with possible exception of *.jpg, *.gif and *.png images). Proposed patch: --------------- Note that it includes unrelated fix for $prevent_xss feature. It would be split in separate patch (non-security related bugfix). With this patch above lol.xml would be served as text/plain... -- >8 -- diff --git i/gitweb/gitweb.perl w/gitweb/gitweb.perl index 240dd47..a3c03f3 100755 --- i/gitweb/gitweb.perl +++ w/gitweb/gitweb.perl @@ -3595,7 +3595,7 @@ sub blob_mimetype { my $fd = shift; my $filename = shift; - if ($filename) { + if ($filename && !$prevent_xss) { my $mime = mimetype_guess($filename); $mime and return $mime; } @@ -6127,7 +6127,7 @@ sub git_blob_plain { # want to be sure not to break that by serving the image as an # attachment (though Firefox 3 doesn't seem to care). my $sandbox = $prevent_xss && - $type !~ m!^(?:text/plain|image/(?:gif|png|jpeg))$!; + $type !~ m!^(?:text/plain(?:; ?charset=.*)|image/(?:gif|png|jpeg))$!; print $cgi->header( -type => $type, -- 8< -- -- Jakub Narebski Poland
Current thread:
- Security issue in gitweb Jamie Strandboge (Jun 03)
- Re: XSS security issue in gitweb for 'blob_plain' view with HTML files Jakub Narebski (Jun 03)
- Re: XSS security issue in gitweb for 'blob_plain' view with HTML files dave b (Jun 03)
- Re: XSS security issue in gitweb for 'blob_plain' view with HTML files Jakub Narebski (Jun 04)
- Re: Re: XSS security issue in gitweb for 'blob_plain' view with HTML files Ludwig Nussel (Jun 14)
- Re: [CVE-2011-2186] XSS security issue in gitweb for 'blob_plain' view with HTML files Jakub Narebski (Jun 14)
- Re: [CVE-2011-2186] XSS security issue in gitweb for 'blob_plain' view with HTML files Ludwig Nussel (Jun 14)
- [CVE-2011-2186] [PATCH] gitweb: Enable $prevent_xss by default Jakub Narebski (Jun 14)
- Re: XSS security issue in gitweb for 'blob_plain' view with HTML files Jakub Narebski (Jun 03)