Document Title:

FTP Drive + HTTP 1.0.4 iOS - Code Execution Vulnerability

References (Source):

http://www.vulnerability-lab.com/get_content.php?id=1231

Release Date:

2014-03-20

Vulnerability Laboratory ID (VL-ID):

1231

Common Vulnerability Scoring System:

9.1

Product & Service Introduction:

FTP Drive + HTTP Server is the ultimate app as for usefullness and ease of use to bring with you and share all your
important files through your iPhone/iPod! When you`re in a hurry or simply wants the things done as they are supposed
to be done, you can use FTP Drive + HTTP Server. As the name implies, you can use this app mainly as an FTP Server,
so you can mount it as a Network Drive in your favorite operative system or you can browse the files through a web
browser like Firefox, Safari, Chrome, Internet Explorer, …

(Copy of the Homepage: https://itunes.apple.com/us/app/ftp-drive-+-http-server-easiest/id455671784 )
(Vendor Homepage: http://www.gummybearstudios.com/ios.html )

Abstract Advisory Information:

The Vulnerability Laboratory discovered a code execution web vulnerability in the official Gummy Bear Studios FTP Drive + HTTP Server v1.0.4 iOS mobile web-application.

Vulnerability Disclosure Timeline:

2014-03-20: Public Disclosure (Vulnerability Laboratory)

Discovery Status:

Published

Affected Product(s):

Exploitation Technique:

Remote

Severity Level:

Critical

Technical Details & Description:

A code execution web vulnerability has been discovered in the official Gummy Bear Studios FTP Drive + HTTP Server v1.0.4 iOS mobile web-application.
The remote vulnerbaility allows an attacker to compromise the application and connected device components by usage of a system specific command execution.

The vulnerability is located in the create folder input field. The input field direct executes the input via GET method request. The request has only a simple
quotes encoding. Remote attackers are easily able to execute code by usage of a script code payload in combination with system device specific php code values.
The execution of the code occurs in the main index file dir listing service context. The attack vector is on application-side and the request method to attack
the service is GET. To bypass the path values validation it is required to first add a folder via `newDir` value. The remote attacker is able to tamper the
create new folder post method request and can intercept the values twice to attach the second manipulated path value to provoke a code execution. After the
add it is possible to attach to the already included values via create new folder to execute the code. The security risk of the remote code execution web
vulnerability is estimated as critical with a cvss (common vulnerability scoring system) count of 9.0(+)|(-)9.1.

Exploitation of the remote code execution web vulnerability requires no privileged application user account (passwd default blank) or user interaction.
Successful exploitation of the code execution vulnerability results in mobile application compromise and connected or affected component compromise.

Vulnerable Module(s):
[+] Create New Folder

Vulnerable Parameter(s):
[+] path value

Proof of Concept (PoC):

The php code execution web vulnerability can be exploited by remote attackers without user interaction or privileged web-application user account.
For security demonstration or to reproduce the vulnerability follow the provided steps and information below to continue.

PoC:
http://localhost:8080/[CONNECTED PATH<]/?newDir=%22[<CODE EXECUTION VULNERABILITY!]#TEST

— PoC Session Logs [GET] —
Status: 200[OK]
GET http://localhost:8080/[CONNECTED PATH<]/?newDir=%22[<CODE EXECUTION VULNERABILITY!]#TEST Load Flags[LOAD_DOCUMENT_URI LOAD_INITIAL_DOCUMENT_URI ] Gro?e des Inhalts[3173] Mime Type[application/x-unknown-content-type]
Request Header:
Host[localhost:8080]
User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:27.0) Gecko/20100101 Firefox/27.0]
Accept[text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8]
Accept-Language[de-de,de;q=0.8,en-us;q=0.5,en;q=0.3]
Accept-Encoding[gzip, deflate]
Referer[http://localhost:8080/[CONNECTED PATH<]/?newDir=%22[<CODE EXECUTION VULNERABILITY!]#TEST]
Connection[keep-alive]
Response Header:
Accept-Ranges[bytes]
Content-Length[3173]
Date[Mi., 19 Mar. 2014 15:06:04 GMT]

Solution - Fix & Patch:

The code execution web vulnerability can be patched by a secure parse of the create new folder input field.
Adjust the encoding of the affected foldername output context value in the main index file dir list.

Security Risk:

The security risk of the remote code execution web vulnerability in the create new folder module is estimated as critical.

Credits & Authors:

Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri ([email protected]) [www.vulnerability-lab.com]

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