D-Link DIR-3060 1.11b04 Command Injection

`IoT Inspector Research Lab Security Advisory IOT-20210311-0  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
title: Authenticated Command Injection in D-Link DIR-3060 Web   
Interface   
vendor/product: D-Link DIR-3060 (https://www.dlink.com/)  
vulnerable version: v1.11b04 & Below  
fixed version: v1.11b04 Hotfix 2  
CVE number: CVE-2021-28144  
impact: 8.8 (high) CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H  
reported: 2020-11-27  
publication: 2021-03-11  
by: T Shiomitsu, IoT Inspector Research Lab  
https://www.iot-inspector.com/  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
Vendor description:  
-------------------  
D-Link Corporation is a Taiwanese multinational networking equipment   
manufacturing corporation. The DIR-3060 (also known as the EXO AC3000 Smart   
Mesh Wi-Fi Router) is one of their higher-end home/small business routers.   
  
  
Vulnerability overview/description:  
-----------------------------------  
The D-Link DIR-3060 is affected by a post-authentication command injection  
vulnerability. Any person who is able to gain authenticated access to a   
DIR-3060 would be able to run arbitrary system commands on the device as the   
system "admin" user, with root privileges.   
  
  
Proof of concept:  
-----------------  
When a SOAP request is made to the SetVirtualServerSettings SOAP endpoint, the  
function at 00461918 in prog.cgi is invoked. This function traverses the SOAP  
XML request body, stores expected SOAP field values, and takes different paths  
depending on the values.   
  
If a request with a non-null LocalIPAddress, Enabled set to “true”, an   
InternalPort of “9” and a ProtocolType of “UDP” is sent, the function   
CheckArpTables (named by me, based at 0046163c) is invoked.  
  
// ...snip   
iVar5 = strcmp(Enabled,"true");   
if ((((iVar5 == 0) && (LocalIPAddress != (char *)0x0)) &&   
(iVar5 = strcmp(InternalPort,"9"), iVar5 == 0)) &&   
(iVar5 = strcmp(ProtocolType,"UDP"), iVar5 == 0)) {   
local_4154 = local_4154 + 1;   
iVar5 = CheckArpTables(LocalIPAddress, InternalPort, ProtocolType, 0xdc, local_4154);   
if (iVar5 == -1) {   
local_4160 = 0xb;   
goto LAB_00462504;   
}   
}   
// ...snip  
  
Interestingly, UDP/9 correlates to the canonical Discard Protocol, which is the  
TCP/UDP/IP equivalent of /dev/null.   
  
The CheckArpTables() function attempts to check the device ARP records, by   
calling the arp system command and grep’ing the output. However, the user-  
controlled value passed as the LocalIPAddress is written directly into the   
command line format string with snprint(). This string is then passed directly  
to a function called FCGI_popen(), which is a library function imported from   
libfcgi.so.  
  
undefined CheckArpTables(char *LocalIPAddress, char *InternalPort, char *ProtocolType, undefined param_4, int param_5) {  
// ...snip...  
memset(buffer, 0, 0x40);  
// ...snip...  
snprintf(buffer, 0x40, "arp | grep %s | awk \'{printf $4}\'", LocalIPAddress);  
iVar1 = FCGI_popen(buffer, "r");  
// ...snip...   
}  
  
We can see in libfcgi.so that FCGI_popen() is essentially only a thin wrapper   
around the stdio popen() library function. Arguments passed to FCGI_popen()   
get passed directly to popen().  
  
  
int FCGI_popen(char *param_1, char *param_2)   
{  
FILE *__stream;   
int iVar1;   
__stream = popen(param_1,param_2);   
iVar1 = FCGI_OpenFromFILE(__stream);   
if ((__stream != (FILE *)0x0) && (iVar1 == 0)) {   
pclose(__stream);   
}   
return iVar1;   
}  
  
Since the LocalIPAddress value is not sanitized or checked in any way, a   
crafted command injection string can be passed as the LocalIPAddress, which   
will then be written to the arp command format string, and passed (almost)   
directly to popen().   
  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
Vulnerable / tested versions:  
-----------------------------  
DIR-3060 v1.11b04  
  
  
Solution:  
---------  
Apply D-Link-supplied patch, v1.11b04 Hotfix 2.  
  
  
Advisory URL:  
-------------  
https://www.iot-inspector.com/blog/advisory-d-link-dir-3060/  
  
  
Vendor contact timeline:  
------------------------  
2020-11-16: Initial contact made to [email protected] to request keys for   
encryption.  
2020-11-20: No reply received, so follow-up e-mail sent.  
2020-11-27: No reply received, so advisory sent by e-mail without encryption.  
2021-02-03: No reply received, so follow-up e-mail sent.  
2021-02-12: No reply received, so inquiry sent using the forms at   
support.dlink.com and eu.dlink.com/uk/en/contact-d-link.  
2021-02-17: Response from the US D-Link support team, pointing us towards the   
US-specific D-Link security page.  
2021-02-17: Sent e-mail to this new US-specific D-Link security e-mail address.  
2021-02-19: Response from a member of the D-Link USA SIRT.  
2021-02-19: We request a public key from D-Link USA for transmission of the   
advisory.  
2021-02-19: PGP public key is provided by D-Link USA.  
2021-02-19: Advisory is sent to D-Link USA with encryption.  
2021-02-19: Receipt of advisory is confirmed by D-Link USA SIRT.  
2021-02-19: We reply and ask for D-Link USA to keep us updated.  
2021-02-20: D-Link “ipsecure” finally answers our e-mail, saying that   
[email protected] should be the official e-mail, and the   
[email protected] e-mail (the only one listed on the main   
D-Link security disclosure page) is only a backup address.  
2021-02-22: D-Link USA responds, confirming that the e-mail address listed   
on the main D-Link security page has been changed.  
2021-03-02: We e-mail D-Link USA to ask for a status update.  
2021-03-02: D-Link USA responds with status update.  
2021-03-08: D-Link USA provides patched firmware for testing.  
2021-03-08: We respond asking for assigned CVE number.  
2021-03-08: D-Link USA notes that they do not apply for, or manage CVE numbers  
related to their own products.  
2021-03-08: We apply for a CVE number for this issue.  
2021-03-08: D-Link USA publishes public advisory.  
2021-03-11: CVE is assigned & IoT Inspector Research Lab publishes advisory.  
  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
The IoT Inspector Research Lab is an integrated part of IoT Inspector.  
  
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checks of IoT firmware. Our mission is to secure the Internet of Things. In   
order to discover vulnerabilities and vulnerability patterns within IoT devices  
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Whenever the IoT Inspector Research Lab discovers vulnerabilities in IoT   
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https://www.iot-inspector.com/responsible-disclosure-policy/  
  
  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  
Interested in using IoT Inspector for your research or product?  
  
Mail: research at iot-inspector dot com  
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EOF T Shiomitsu / @2021  
  
  
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