Perli 2.6 Filter Bypass / Script Insertion

Type packetstorm
Reporter Benjamin Kunz Mejri
Modified 2016-04-08T00:00:00


Document Title:  
Perli v2.6 iOS - Filter Bypass & Persistent Vulnerability  
References (Source):  
Release Date:  
Vulnerability Laboratory ID (VL-ID):  
Common Vulnerability Scoring System:  
Product & Service Introduction:  
This is an ios perl app,you can learn,run,share perl script. In(the  
built-in browser or the txt editor),Select the text to run.  
(Copy of the Homepage: )  
Abstract Advisory Information:  
The Vulnerability Laboratory Core Research Team discovered an  
application-side encoding vulnerability in the official Perli iOS mobile  
application api.  
Vulnerability Disclosure Timeline:  
2016-04-05: Public Disclosure (Vulnerability Laboratory)  
Discovery Status:  
Affected Product(s):  
XiaoWen Huang  
Product: Perli - Perl Editor & Compiler iOS (Application) 2.6  
Exploitation Technique:  
Severity Level:  
Technical Details & Description:  
A persistent input validation and mail encoding vulnerability has been  
discovered in the Perli iOS mobile application api.  
The persistent web vulnerability allows to inject malicious script codes  
to the application-side of the vulnerable modules.  
The basic validation of the code formular and mask allows to include any  
type of script codes or programming language without  
offensive input restrictions. Attackers can inject code to a project to  
share it with another source. In the moment the code  
of the project is generated to the email body, a persistent script code  
execution occurs.  
There are two options to exploit, first is to send the malicious mail to  
the author of the program by the `Mail Author` function.  
Another possibility to execute code in the email body context is to  
share it with another code editor by email. In both email body  
message context the injected wrong filtered script code execution  
occurs. The internal encoding of the formular is correctly done  
but in case of sharing by qr or via message body email the execution  
occurs. The vulnerability is located on the application-side  
of the iOS application and the request method to inject requires  
physical device access or access to the share function. The bug  
is present in the perli 2.6 version of the mobile client. Attackers can  
for example generate a QR code with malicious context that  
is executed in the message body were the code is mainly displayed by the  
iOS application.  
The security risk of the application-side vulnerability is estimated as  
medium with a cvss (common vulnerability scoring system) count of 3.5.  
Exploitation of the persistent vulnerability requires a low privileged  
ios device user account with restricted access and low user interaction.  
Successful exploitation of the vulnerabilities results in persistent  
phishing mails, session hijacking, persistent external redirect to  
sources and application-side manipulation of affected or connected  
module context.  
Vulnerable Module(s):  
[+] Share to Authors  
[+] Share by Email  
[+] Share via QR Code  
Vulnerable Function(s):  
[+] Console  
[+] Perli  
Proof of Concept (PoC):  
The persistent vulnerability and mail encoding bug can be exploited by  
remote attackers with low privileged device user account and low user  
For security demonstration or to reproduce the vulnerability follow the  
provided information and steps below to continue.  
Manual steps to reproduce the vulnerability ...  
1. Install the perl app to your apple iOS device  
2. Start the mobile application  
3. Include to the first variable in the demo code java or html script  
code and save the entry as perl script  
4. Open the saved entry again and click the top right arrow menu  
5. Now choose Create QR or Share menu button  
6. Open the menu `Mail to Author` or push the default `iOS Mail App` button  
7. Now the code of the formular gets transfered to the email message  
body context  
Note: The encoding does not parse or encode any inserted values  
8. The email arrives to the target inbox  
9. Open the email and the code executes directly in the message body or  
next to the generated qr code  
10. Successful reproduce of the filter and validation vulnerability in  
the perli app!  
Note: The bug can be exploited by sending to the author, by sending to  
another target mail or by transfer of a qr code.  
PoC: Perli Editor  
$aa = <STDIN>;  
print($"><iframe onload=alert("TEST")>%20"><iframe  
Note: The same type of vulnerability has been disclosed in a python  
editor as well.  
VL ID: 1806 (  
Solution - Fix & Patch:  
The vulnerability can be patched by a secure parse and encode of the  
vulnerable message body context.  
Filter and parse all code values that are included to the message body.  
Configure the code to plain text not html to prevent further persistent  
injection attacks.  
In case of emergency use the escape function to separate the mechanism  
Security Risk:  
The security risk of the filter bypass and persistent encoding web  
vulnerability in the perli ios app is estimated as medium. (CVSS 3.5)  
Credits & Authors:  
Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri  
( []  
Disclaimer & Information:  
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