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From "Robert Newson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (COUCHDB-2221) malformed iterations field in _users doc causes authentication hang
Date Sun, 06 Apr 2014 17:20:15 GMT

    [ https://issues.apache.org/jira/browse/COUCHDB-2221?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13961464#comment-13961464
] 

Robert Newson commented on COUCHDB-2221:
----------------------------------------

For clarity, I don't think CouchDB should accept malformed user docs. If the field is malformed
in any way we should either refuse to authenticate (send 401) or fallback to a sane, well-formed
default in code. e.g;

https://gist.github.com/rnewson/10008876

Fixing this for one field is a step in the right direction but we should iterate a little
to cover all the auth-related fields in _users docs and include generic functions for this.
For example, we could write couch_util:get_int_value(Key, List, Default) with the defined
behaviour that you get Default if there's no entry in the list or if the value associate with
Key is not an integer. The function will throw an exception if Default is not an integer.

The fundamental bug here is that the code continued on using a string when an int was required
and, as @wohali notes, there's no int that sorts higher than a string. The minimum fix is
a proper crash. I'm averse to adding error-handling code for specific examples of general
problems.


> malformed iterations field in _users doc causes authentication hang
> -------------------------------------------------------------------
>
>                 Key: COUCHDB-2221
>                 URL: https://issues.apache.org/jira/browse/COUCHDB-2221
>             Project: CouchDB
>          Issue Type: Bug
>      Security Level: public(Regular issues) 
>          Components: Database Core
>            Reporter: Isaac Z. Schlueter
>            Assignee: Joan Touzet
>
> Create a user account with the following details:
> {
>   "_id":"org.couchdb.user:test-user",
>   "name":"test-user",
>   "password":"this is a test"
>   "roles":[],
>   "type":"user"
> }
> CouchDB will PBKDF2-ify the password in the _users doc.  So far so good.
> Then, try this:
> ubuntu@ip-172-31-35-228:~$ curl http://localhost:5984/_users/org.couchdb.user:test-user
-u "test-user:this is not the correct password" -vvv
> * About to connect() to localhost port 5984 (#0)
> *   Trying 127.0.0.1... connected
> * Server auth using Basic with user 'test-user'
> > GET /_users/org.couchdb.user:test-user HTTP/1.1
> > Authorization: Basic dGVzdHVzZXI6dGhpcyBpcyBub3QgdGhlIGNvcnJlY3QgcGFzc3dvcmQ=
> > User-Agent: curl/7.22.0 (x86_64-pc-linux-gnu) libcurl/7.22.0 OpenSSL/1.0.1 zlib/1.2.3.4
libidn/1.23 librtmp/2.3
> > Host: localhost:15984
> > Accept: */*
> >
> And then it hangs indefinitely.
> This does not happen when the user account uses password_sha.  For example:
> ubuntu@ip-172-31-35-228:~$ curl http://localhost:15984/_users/org.couchdb.user:testuserasdf
-u "testuserasdf:this is not the correct password" -vvv
> * About to connect() to localhost port 15984 (#0)
> *   Trying 127.0.0.1... connected
> * Server auth using Basic with user 'testuserasdf'
> > GET /_users/org.couchdb.user:testuserasdf HTTP/1.1
> > Authorization: Basic dGVzdHVzZXJhc2RmOnRoaXMgaXMgbm90IHRoZSBjb3JyZWN0IHBhc3N3b3Jk
> > User-Agent: curl/7.22.0 (x86_64-pc-linux-gnu) libcurl/7.22.0 OpenSSL/1.0.1 zlib/1.2.3.4
libidn/1.23 librtmp/2.3
> > Host: localhost:15984
> > Accept: */*
> >
> < HTTP/1.1 401 Unauthorized
> < Server: CouchDB/1.5.0 (Erlang OTP/R14B04)
> < Date: Sat, 05 Apr 2014 22:58:54 GMT
> < Content-Type: text/plain; charset=utf-8
> < Content-Length: 67
> < Cache-Control: must-revalidate
> <
> {"error":"unauthorized","reason":"Name or password is incorrect."}
> * Connection #0 to host localhost left intact
> * Closing connection #0
> This is a serious and urgent problem for npm.
> At the urging of many people in the CouchDB and Node.js community, we've been migrating
users to pbkdf2 accounts.  However, rather than quickly report authorization failures, it
hangs indefinitely, and eventually our TLS terminator returns a 500 or our CDN returns a 503.
> Because the appropriate HTTP response code is not being returned, we cannot hope to properly
handle the situation.  It looks like the server has just fallen over.  Already the user experience
has started to get pretty awful.
> What's worse, I fear that this is a DOS exploit, because it ties up a connection for
a very long time.  The npm registry is somewhat insulated by our CDN, but any CouchDB using
pbkdf2 password storage is vulnerable.



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