Gogs Label Search Blind SQL Injection

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Blind SQL Injection in Gogs label 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 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 <[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-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  
PGP-FP 971B D4F7 5DD1 FCED 11FC 2C61 7AB6 927D 6F26 6CE0  
  
Handelsregister Mannheim: HRB 337135  
Geschaeftsfuehrer: Enno Rey  
  
==============================================================  
|| Blog: www.insinuator.net | | Conference: www.troopers.de ||  
==============================================================  
================== TROOPERS15 ==================  
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* 16th - 20st March 2015 / Heidelberg, Germany  
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====================================================  
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