Gogs (label pararm) - SQL Injection

Blind SQL Injection in Gogs label search

========================================

Researcher: Timo Schmid <tschmid@ernw.de>





Description

===========

Gogs(Go Git Service) is a painless self-hosted Git Service written in

Go. (taken

from [1])



It is very similiar to the github hosting plattform. Multiple users can

create

multiple repositories and share code with others with the git version

control

system. Repositories can be marked as public or private to prevent

access from

unauthorized users.



Gogs provides a view to filter issues by labels. This view is accessible at

/<username>/<repository>/issues?labels=&type=&state=



The labels Parameter of this view is vulnerable to a blind SQL injection.





Exploitation Technique:

=======================

Remote





Severity Level:

===============

Critical





CVSS Base Score

===============

6.6 (AV:N / AC:H / Au:N / C:C / I:P / A:P)





CVE-ID

======

CVE-2014-8681





Impact

======

The vulnerability results at least in a complete compromise of the database.

Depending on the particular database configuration a compromise of the

system

is also possible.





Status

======

Fixed by Vendor





Vulnerable Code Section

=======================

models/issue.go:

[...]

// GetIssues returns a list of issues by given conditions.

func GetIssues(uid, rid, pid, mid int64, page int, isClosed bool, labelIds,

sortType string) ([]Issue, error) {

    sess := x.Limit(20, (page-1)*20)



    if rid > 0 {

        sess.Where("repo_id=?", rid).And("is_closed=?", isClosed)

    } else {

        sess.Where("is_closed=?", isClosed)

    }



    if uid > 0 {

        sess.And("assignee_id=?", uid)

    } else if pid > 0 {

        sess.And("poster_id=?", pid)

    }



    if mid > 0 {

        sess.And("milestone_id=?", mid)

    }



    if len(labelIds) > 0 {

        for _, label := range strings.Split(labelIds, ",") {

            sess.And("label_ids like '%$" + label + "|%'")

        }

    }

[...]



The vulnerability exists because of a string concatination in the SQL

query with

user supplied data. A attacker is restricted to not use commas in the

injection

string as the program splits input at commas.





Proof of Concept

================

Test of version string contains at least 10 characters:

http://www.example.com/user/repos/issues?label=' or

char_length(@@version) > 10

and '|%'='&type=all&state=



Returns all issues if true, non if false.



This could be used to extract data with a binary search.





Solution

========

This vulnerability could easily be fixed by using prepared statements:



sess.And("label_ids like ?", "%$" + label + "|%")



Update to Version 0.5.6.1025.



Affected Versions

=================

>= v0.3.1-9-g49dc57e

<= v0.5.6.1024-gf1d8746





Timeline

========

2014-09-25: Developer informed

2014-10-16: Contact of developer regarding fix

2014-10-25: Working together with developer on fix

2014-10-25: Fixed by ensuring datatype of user input

2014-11-14: CVE-ID assigned





Credits

=======

Pascal Turbing <pturbing@ernw.de>

Jiahua (Joe) Chen <u@gogs.io>





References

==========

[1] https://github.com/gogits/gogs

[2] http://gogs.io/

[3]

http://www.insinuator.net/2012/05/sql-injection-testing-for-business-purposes-part-1/

[4]

http://www.insinuator.net/2012/05/sql-injection-testing-for-business-purposes-part-2/

[5]

http://www.insinuator.net/2012/06/sql-injection-testing-for-business-purposes-part-3/

[6] https://www.ernw.de/download/BC-1401.txt





Advisory-ID

===========

BC-1401





Disclaimer

==========

The information herein contained may change without notice. Use of this

information constitutes acceptance for use in an AS IS condition. There

are NO

warranties, implied or otherwise, with regard to this information or its

use.

Any use of this information is at the user's risk. In no event shall the

author/

distributor be held liable for any damages whatsoever arising out of or in

connection with the use or spread of this information.



--

Timo Schmid



ERNW GmbH, Carl-Bosch-Str. 4, 69115 Heidelberg  -  www.ernw.de

Tel. +49 6221 480390 - Fax 6221 419008 - Cell +49 151 16227192

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Handelsregister Mannheim: HRB 337135

Geschaeftsfuehrer: Enno Rey



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