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Date: Tue, 2 Aug 2016 16:09:46 +0200
From: Marcus Meissner <meissner@...e.de>
To: oss-security@...ts.openwall.com
Subject: Re: Ruby:HTTP Header injection in 'net/http'

Hi,

was this ever accepted by the Ruby upstream team as valid bug?

You seem to quote some bugtracker, where is it and is the bug public there?

Ciao, Marcus
On Sat, Jun 25, 2016 at 12:18:42PM +0800, redrain root wrote:
> TIMELINE
> rootredrain submitted a report to Ruby.
> 
> show raw
> Jun 22nd
> 
> Hi,
> 
> I would like to report a HTTP Header injection vulnerability in
> 'net/http' that allows attackers to inject arbitrary headers in
> request even create a new evil request.
> 
> PoC
> 
> require 'net/http'
> http = Net::HTTP.new('192.168.30.214','80')
> res = http.get("/r.php HTTP/1.1\r\nx-injection: memeda")
> 
> Example
> 
> Server Code:
> 
> #!/usr/bin/env ruby
> require 'sinatra'
> require 'uri'
> require 'net/http'
> 
> get '/' do
>   'hello world'
> end
> 
> post '/' do
>   ip = params[:ip]
>   port = params[:port]
>   path = params[:path]
> 
>   # do what you want
>   http = Net::HTTP.new ip, port.to_i
>   res = http.get path
> 
>   res.body
> 
> end
> 
> post data:
> 
> ip=192.168.30.214&port=80&path=/r.php%20HTTP/1.1%0d%0ax-injection: memeda
> 
> print_r all HTTP Headers:
> 
> Create an evil request
> 
> post data:
> 
> server log:
> 
> Suggestion:
> 
> Should validate URI legality before send request
> 
> btw,
> 
> Cloud I have a CVEID with this vulnerability? reported by
> @redrain(rootredrain@...il.com) and@...(ztz5651483@...il.com)
> 
> 4 attachments:
> F100918: 123123.png
> F100919: 222333.png
> F100920: 4444.png
> F100921: 5555.png
> 
> rootredrain posted a comment.
> Jun 22nd (2 days ago)
> 
> The problem is this line in lib/net/http/generic_request.rb:324
> 
>   def write_header(sock, ver, path)
>     buf = "#{@...hod} #{path} HTTP/#{ver}\r\n"
>     each_capitalized do |k,v|
>       buf << "#{k}: #{v}\r\n"
>     end
>     buf << "\r\n"
>     sock.write buf
>   end
> 
> "#{@...hod} #{path} HTTP/#{ver}\r\n" should be checked here to avoid
> malicious input
> 
> shugo posted a comment.
> Jun 24th (8 hrs ago)
> 
> Thanks for your report.
> 
> We don't consider this a vulnerability because Net::HTTP#get is not
> designed to accept malicious input.
> Applications have responsibility to verify input syntactically and
> semantically (accepting all RFC2616-compliant input would not be a
> good idea).
> 
> So we would like to handle this as a normal issue.
> 
> rootredrain posted a comment.
> Jun 24th (2 hrs ago)
> 
> Hi shugo,
> 
> Thanks for the reply. Please don't leave this problem to developers,
> they have uneven level at developing.
> 
> For example, assume we have a demo website, the only thing do is
> generate a new HTTP request:
> 
> #!/usr/bin/env ruby
> require 'sinatra'
> 
> get '/' do
>   'hello world'
> end
> 
> post '/' do
>   ip = params[:ip]
>   port = params[:port]
>   path = params[:path]
> 
>   # send the request to another site
>   http = Net::HTTP.new ip, port.to_i
>   res = http.get path
> 
>   res.body
> end
> 
> It's a common demand, right ?
> 
> But web developer may not realized that sinatra will auto decode url.
> Attacker can encode \r\n to %0a%0d, send to the sinatra, sinatra will
> decode url to \r\n and pass to thepath, finally cause a HTTP Header
> Injection or CRLF Injection.
> 
> Please assume all input is malicious. Here is a similar vulnerability
> in python: CVE-2016-5699
> 
> Here is what another HTTP lib Faraday do may change your mind.
> 
> lib/faraday/connection.rb:308
> 
> def url_prefix=(url, encoder = nil)
>   uri = url_prefix = Utils.URI(url)
>   self.path_prefix = uri.path
>   # ... ... ...
>   uri
> end
> 
> uri = url_prefix = Utils.URI(url) try to convert url to URI, It will
> raise an error whenurl is invalid.
> 
> lib/faraday/connection.rb:399
> 
> def build_exclusive_url(url = nil, params = nil, params_encoder = nil)
>   url = nil if url.respond_to?(:empty?) and url.empty?
>   base = url_prefix
>   # ... ... ...
>   uri = url ? base + url : base
>   # ... ... ...
> end
> 
> uri = url ? base + url : base will trigger another examination convert_to_uri:
> 
> def convert_to_uri(uri)
>   if uri.is_a?(URI::Generic)
>     uri
>   elsif uri = String.try_convert(uri)
>     parse(uri)
>   else
>     raise ArgumentError,
>           "bad argument (expected URI object or URI string)"
>   end
> end
> 
> If url is invalid, it will raise an error.
> 
> Please let me know if you need more info.
> 
> tenderlove posted a comment.
> Jun 24th (2 hrs ago)
> 
> It's a common demand, right ?
> 
> I'm not sure about that.
> 
> I think this is a bug we should probably address, but I don't think we
> should consider this a vulnerability. Fetching arbitrary paths from
> user input seems pretty dubious.
> 
> rootredrain posted a comment.
> Jun 24th (about 1 hr ago)
> 
> Hi tenderlove,
> 
> Here is my point :
> All input can not be trusted.
> 
> We should validate url in Net::HTTP
> 
> tenderlove posted a comment.
> Jun 24th (about 1 hr ago)
> 
> All input can not be trusted.
> 
> Yes, people should be whitelisting paths passed in. An open proxy is
> already a vulnerability, regardless of header injection.
> 
> As I said, we should treat this as a bug. But since an open proxy is
> already a security problem (that we cannot fix), then I don't think
> this bug should be treated as a security issue.
> 
> shugo posted a comment.
> Jun 24th (34 mins ago)
> 
> But web developer may not realized that sinatra will auto decode url.
> Attacker can encode \r\n to %0a%0d, send to the sinatra, sinatra will
> decode url to \r\n and pass to the path, finally cause a HTTP Header
> Injection or CRLF Injection.
> 
> In that case, it seems to be a bug of that application, not Net::HTTP#get.
> 
> I'm not against adding argument verification to Net::HTTP#get, though.
> 
> rootredrain posted a comment.
> Jun 24th (29 mins ago)
> 
> But since an open proxy is already a security problem
> 
> Yes, an open proxy is already a vulnerability and you can't fix that,
> but attack scenarios is not only include an open proxy, but also
> include many other parts.
> 
> A site like google image, user can paste image url on it, then site
> will request the resource. It's possible to suffer this attack.
> 
> Some video sites allow user reference outside resource. It's possible
> to suffer this attack.
> 
> So you can not treat it occur in an unusual scenarios. I still
> consider it was a security issue.
> 
> rootredrain posted a comment.
> Jun 24th (27 mins ago)
> 
> If you believe this is not a issue, please allow the public disclosure.
> 
> tenderlove closed the report and changed the status to Informative.
> Jun 24th (23 mins ago)
> 
> I've closed as informative, and I'll allow public disclosure.
> 
> tenderlove requested to disclose this report publicly.
> Jun 24th (20 mins ago)
> 
> rootredrain has requested mediation from HackerOne Support.
> Jun 24th (15 mins ago)
> 
> The HTTP scheme handler accepts percent-encoded values as part of the URL.
> 
> The generic_request.rb allows unsafe characters, it dosen't have any
> safe filtration, attackers can cause actual security threat. so we
> consider it is a vulnerability
> 

-- 
Marcus Meissner,SUSE LINUX GmbH; Maxfeldstrasse 5; D-90409 Nuernberg; Zi. 3.1-33,+49-911-740 53-432,,serv=loki,mail=wotan,type=real <meissner@...e.de>

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