Easy FTP Pro 4.2 iOS – Command Injection

Document Title:

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

Easy FTP Pro v4.2 iOS - Command Inject Vulnerabilities

References (Source):

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

http://www.vulnerability-lab.com/get_content.php?id=1291

Release Date:

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

2014-08-06

Vulnerability Laboratory ID (VL-ID):

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

1291

Common Vulnerability Scoring System:

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

5.7

Product & Service Introduction:

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

The Best FTP and SFTP client for iPhone and iPad! Easy FTP is an FTP (File Transfer Protocol) and SFTP client for

iPhone/iPod Touch. Easy FTP offer all the features of a desktop client. Also includes a web browser that allow to

download files, audio player, mp4, avi,... video player, Dropbox, also helps you to access files on your remote

computer (Mac, Windows, Linux), NAS Servers, and more.

( Copy of the Homepage: https://itunes.apple.com/en/app/easy-ftp-pro/id429071149 )

Abstract Advisory Information:

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

The Vulnerability Laboratory Research Team discovered two command injection web vulnerabilities in the official Easy FTP Pro v4.2 iOS mobile application.

Vulnerability Disclosure Timeline:

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

2014-08-06: Public Disclosure (Vulnerability Laboratory)

Discovery Status:

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

Published

Affected Product(s):

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

Juan Ramon Rivero

Product: Easy FTP Pro - iOS Mobile Web Application 4.2

Exploitation Technique:

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

Remote

Severity Level:

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

Medium

Technical Details & Description:

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

Two local command inject web vulnerabilities has been discovered in the official Easy FTP Pro v4.2 iOS mobile application.

The vulnerability allows remote attackers to inject own commands by usage of misconfigured stored system/device values to

compromise the apple mobile iOS application.

The first vulnerability is located in the vulnerable `foldername` value of the `easy ftp wifi` module. Local attackers are

able to inject own malicious system specific commands or path value requests in the vulnerable `foldername` input value.

The execution of the command occurs in the `File Dir Index Listing` module of the easy ftp pro v4.2 mobile application.

The attacker is able to manipulate the local device values with physical or restricted acccess to compromise the mobile

application by preparing to change the foldername. The encoding of the vulnerable values in the `File Dir Index Listing`

module is broken.

The second vulnerability is also located in the `�asy ftp wifi` module. The same attack like on changing a foldername can

be exploited by attacker through the regular filename validation. The attacker is able to manipulate the local device values

with physical or restricted acccess to compromise the mobile application by preparing to change the filename.

The attack vector is located on the application-side and the injection requires physical device access or a local low

privileged device user account. Local attackers are also able to exploit the albumname validation issue in combination

with persistent injected script codes.

The security risk of the local command/path inject vulnerability is estimated as medium with a cvss (common vulnerability

scoring system) count of 5.7. Exploitation of the command/path inject vulnerability requires a low privileged iOS device

account with restricted access and no user interaction. Successful exploitation of the vulnerability results in unauthorized

execution of system specific commands and unauthorized path value requests to compromise the mobile iOS application or the

connected device components.

Request Method(s):

[+] [Sync]

Vulnerable Module(s):

[+] Add File & Rename File + Import

[+] Add Folder & Rename Folder + Import

Vulnerable Parameter(s):

[+] foldername

[+] filename

Affected Module(s):

[+] File Dir Index Listing

Proof of Concept (PoC):

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

The local command inject web vulnerabilities can be exploited by local attackers with low privileged or restricted device user account

with physical access and without user interaction. For security demonstration or to reproduce the vulnerability follow the provided

information and steps below to continue.

PoC #1:

--- PoC Session Logs [GET] (Execution) ---

Status: pending[]

GET http://localhost:8080/[LOCAL COMMAND INJECT VULNERABILITY!] Load Flags[VALIDATE_ALWAYS ] Gr��e des Inhalts[unknown] Mime Type[unknown]

Request Header:

Host[localhost:8080]

User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:31.0) Gecko/20100101 Firefox/31.0]

Accept[image/png,image/*;q=0.8,*/*;q=0.5]

Accept-Language[de,en-US;q=0.7,en;q=0.3]

Accept-Encoding[gzip, deflate]

Referer[http://localhost:8080/]

12:26:56.763[0ms][total 0ms]

Status: 200[OK]

GET http://localhost:8080/index Load Flags[LOAD_DOCUMENT_URI ] Gr��e des Inhalts[unknown] Mime Type[unknown]

Request Header:

Host[localhost:8080]

User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:31.0) Gecko/20100101 Firefox/31.0]

Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8]

Accept-Language[de,en-US;q=0.7,en;q=0.3]

Accept-Encoding[gzip, deflate]

Referer[http://localhost:8080/]

12:27:11.166[0ms][total 0ms] Status: Aus dem Cache geladen[Aus dem Cache geladen]

GET http://localhost:8080/# Load Flags[LOAD_FROM_CACHE ] Gr��e des Inhalts[-1] Mime Type[unbekannt]

Request Header:

Host[localhost:8080]

User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:31.0) Gecko/20100101 Firefox/31.0]

Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8]

Accept-Language[de,en-US;q=0.7,en;q=0.3]

Accept-Encoding[gzip, deflate]

PoC: Source Foldername - File Dir Index Listing

function eliminaArchivo(archNombre){

$.post("/delete/"+archNombre,

function(data) {

cargaLista(rutaActual);

});

}

function comprueba(){

var fullPath = document.getElementById('uploadFile').value;

if (fullPath) {

var startIndex = (fullPath.indexOf('\\') >= 0 ? fullPath.lastIndexOf('\\') : fullPath.lastIndexOf('/'));

var filename = fullPath.substring(startIndex);

if (filename.indexOf('\\') === 0 || filename.indexOf('/') === 0) {

filename = filename.substring(1);

}

filenombre = filename;

}

return true;

}

var rutaActual = '';

function confirma(nombre){

var borrar = confirm("Do you really want to delete: "+unescape(nombre)+"?");

if (borrar == true){

//return true;

eliminaArchivo(nombre);

}

return false;

}

function cargaLista(ruta){

$("#filelist").empty();

$("#folder").empty();

var send = ruta;

if(ruta == '..'){

if(rutaActual.lastIndexOf('/')>=0)

send = rutaActual.substr(0,rutaActual.lastIndexOf('/'));

else

send = '';

}

$.ajaxSetup({cache: false});

$.getJSON('/files/'+send/*'/files/'+ruta*/,

function(data){

var shadow = false;

//console.log(data);

rutaActual = data.currentDir;

$('#folder').append('Current path: Documents/' +data.currentDir);

$.each(data.files, function(i,item){

var trclass='';

if (shadow)

trclass= " class='shadow'";

encodeName = (encodeURI(rutaActual)+'/'+item.name).replace("'", "'");

var html = '';

if(item.type == 'FILE')

html += "<tr" + trclass + "><td class='icon'> </td><td class='filename'><a href='https://www.exploit-db.com/files/" + encodeName + "' class='file'>" +

decodeURI(item.name) + "</a></td>" + "<td class='size'>" + item.tam + "</td>";else

html += "<tr" + trclass + "><td class='icon'><img src=\"folder.png\" alt=\"folder\" height=20 width=20 /></td><td class='filename'>

<a href='javascript:cargaLista(\"" + encodeURI(item.path).replace("'", "'") + "\")' class='file'>" + decodeURI(item.name) + "</a></td>"+"<td class='size'> </td>";

html += "<td class='date'>" + item.date + "</td>" +

"<td class='del'><a href='https://www.exploit-db.com/exploits/34305/#' onclick='confirma(\""+escape(decodeURI(encodeURI(rutaActual)+'/'+item.name)).replace("'", "'")+"\")'><img src=\"delete.gif\"

alt=\"folder\" height=20 width=20 style=\"border:0;\" /></a></td></tr>";

$(html).appendTo("#filelist");

shadow = !shadow;

});

})

.error(function(){

alert('Connection error. Check if the web sharing is on and the iphone/ipod still connected to the network.');

});

}

$.ajaxSetup({cache: true});

$(document).ready(function(){

cargaLista('');

});

</script>

PoC #2:

--- PoC Session Logs [GET] (Execution) ---

Status: 200[OK]

GET http://localhost:8080/files/%3[LOCAL COMMAND INJECT VULNERABILITY!]_=1407321412178 Load Flags[LOAD_BACKGROUND VALIDATE_ALWAYS ] Gr��e des Inhalts[42] Mime Type[application/x-unknown-content-type]

Request Header:

Host[localhost:8080]

User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:31.0) Gecko/20100101 Firefox/31.0]

Accept[application/json, text/javascript, */*; q=0.01]

Accept-Language[de,en-US;q=0.7,en;q=0.3]

Accept-Encoding[gzip, deflate]

X-Requested-With[XMLHttpRequest]

Referer[http://localhost:8080/]

Connection[keep-alive]

Response Header:

Accept-Ranges[bytes]

Content-Length[42]

Date[Wed, 06 Aug 2014 10:37:15 GMT]

Status: pending[]

GET http://localhost:8080/..%3C/[LOCAL COMMAND INJECT VULNERABILITY!] Load Flags[LOAD_DOCUMENT_URI ] Gr��e des Inhalts[unknown] Mime Type[unknown]

Request Header:

Host[localhost:8080]

User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:31.0) Gecko/20100101 Firefox/31.0]

Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8]

Accept-Language[de,en-US;q=0.7,en;q=0.3]

Accept-Encoding[gzip, deflate]

Referer[http://localhost:8080/]

PoC: Source Filename - File Dir Index Listing

<thead>

<tr>

</th>

Name

</th>

Size

</th>

Modified

</th>

</th>

</tr>

</thead>

</table>

<a href="javascript:cargaLista("h[LOCAL COMMAND INJECT VULNERABILITY!])" class="file">[LOCAL COMMAND INJECT VULNERABILITY!]"></a></td>

Solution - Fix & Patch:

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

The vulnerabilities can be patched by a secure parse and encode of the vulnerable file- and foldername values.

Restrict the local app user input on both values to prevent further command injection attacks. Do not forget to parse the affected output listing in the file dir listing.

Security Risk:

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

The security risk of both command inject web vulnerabilities in the file- and foldername values are estimated as medium(+).

Credits & Authors:

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

Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri (bkm@evolution-sec.com) [www.vulnerability-lab.com]

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

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