Security & Trust


TLSAssistant is a modular extensive framework that combines state-of-the-art TLS analyzers with a report system that suggests appropriate mitigations and shows the full set of viable attacks. It is open-source, released under Apache-2.0 license and and you can contribute by visiting the project’s repository.

The tool has been developed within Digimat, a joint lab between Poligrafico e Zecca dello Stato and the Center for Cybersecurity of the Fondazione Bruno Kessler.




TLSAssistant v3 is the latest release of our state-of-the-art analyzer able to help system administrators and Android app developers in correctly configuring their TLS deployments. This version expands the software’s capabilities by adding a new analysis module able to assess the compliance level of TLS deployments, comparing them to national agencies-issued guidelines. The new update also comes with an improved output module, which is now able to generate structured PDF reports.

It currently integrates five tools:

To have a deeper understanding of the architecture, we must first grasp how it is organized.

TLSAssistant makes advantage of the idea of a “Module,” which is a collection of objects and classes that are joined in the same file by context (e.g., the type of vulnerability analyzed). Each module adheres to standards that must be followed in order to develop a compliant module.

We have different type of modules

  • Analysis Modules: modules that perform the analysis using independent code or external tools. This type of module will employ a submodule called wrapper to interface with external tools. The output module receives the Analysis module’s output.
    • Wrapper Modules: modules that wrap an external software or an API call. Given that output must be refined by the Analysis module, a wrapper should not be directly connected to the output module. Most of the time, the wrapper is an entire API of non-Python software.
  • Core Module: the modules’ router. It parses the specified configuration, runs each module, gathers the output and redirects it to the output module.
  • Output Module: formats the output properly by according to the mitigation standard and the provided information.

How To Contribute

In order to contribute to the project, allowing the Core module to automatically detect and integrate the new changes, the developer must follow the provided standards:

List of modules

Wrapper Modules

Module name Wraps subprocess call
HSTS HTTPS API Call to check HSTS SET, Preloading and HTTPS Enforcement. Can be used to obtain information about the webserver.
tlsfuzzer tlsfuzzer script selection and call, following parameters and parsing output.
Certificate Subdomain enumeration by API call. Useful for *.mysite.tld
TLS-Scanner TLS-Scanner subprocess call

Analysis Modules

Module Name Wrapper Used
CCS Injection
Certificate Transparency
HSTS preloading HSTS HTTPS
Perfect Forward Secrecy
TLSPoodle TLS-Scanner
SLOTH tlsfuzzer

Wrapper Modules

Module Name Wraps
mallodroid Mallodroid python3 import and call.
SUPERAnalyzer SUPERAnalyzer subprocess call.

Analysis Modules

Module Name Wrapper Used
Accepting all SSL Certificates SUPERAnalyzer
Certificate or KeyStore Disclosure SUPERAnalyzer
Weak HostnameVerifier mallodroid
Obfuscated Code SUPERAnalyzer
SSL GetInsecure Method SUPERAnalyzer
SSL Error mallodroid
Weak TrustManager mallodroid
Weak Algorithms SUPERAnalyzer
WebView has SSL Errors SUPERAnalyzer
Module Name Type
Core Core
Stix Output
Configuration Core
Parse Input Configuration Core
Report Output

Compliance Modules

Module Name Type Wrapper Used
compare_one Comparison
compare_many Comparison
generate_one Generation -
generate_many Generation -


In this architecture, we have two different flow:

  • Flow of the developer:

    To add a new Analysis module (see left of Architecture Figure), the developer must follow the provided standard. As a result, the new functionality will be detected and implemented by the Core module. In addition to providing the code for implementing the tests for identifying a vulnerability, if a mitigation is known, the developer should define it by producing a JSON file in accordance with the mitigation standards.

  • Flow of the end-user:

    The end-user decides which modules to utilize in the analysis in Step 1 (see right of Architecture Figure) by supplying a configuration file or a command line list. Each configuration file is a context-specific collection of modules that conducts a certain kind of analysis (e.g., checking for vulnerabilities related to weak TLS ciphers). Step 2: The Core loads the configuration (if supplied) and the modules (from the list or configuration), ensuring that they are relevant to the kind of analysis requested.

Type of Analysis

Here a quick overview of the various types of analysis that may be requested:

  1. Single Host: Because the program covers the majority of the vulnerabilities assessed by the tool, we decided to make the analysis more efficient by doing a pre-analysis (Step 3a) to create a cache with its results. During current and future analysis, they will be utilized by each of the related modules (Step 3b), such as POODLE (an attack that uses the availability of SSLv3 to weaken the connection).
  2. Single APK: Each Android-related module, such as Unsecure TrustManager, performs the analysis (Step 3b) on the given APK.
  3. Multiple Hosts: On each of the domains supplied in an input list, we execute a Single Host analysis. Each result is concatenated and delivered as a single output to the Output module. The list can also be generated by subdomain enumeration.
  4. TLS Configuration and Fixes: If a configuration file is given, a WhiteBox analysis is conducted by loading the TLS configuration into memory and checking all accessible modules (Step 3b). Otherwise, if a configuration file and a valid hostname are given, a single host analysis is conducted, and the corrections are then merged into the provided TLS configuration. This is referred to as a Hybrid study since we run a BlackBox analysis on the hostname and then apply the changes to the configuration file.

Compliance Analysis

TLSAssistant is able to perform an automated compliance analysis against five agency-issued technical guidelines:

  • AgID ver.2020-01
  • ANSSI v1.2
  • BSI TR-02102-2 and TR-03116-4
  • Mozilla v5.7
  • NIST SP 800-52 Rev. 2 (and related)

    Comparison Modules

    The compare_one and compare_many modules are used to assess the compliance level of an existing webserver (both deployed and not) against one or multiple guidelines. Its output consists of an actionable report that combines a description of the potential lack of compliance along with an explanation on how improve the security posture of the analyzed server and a set of actionable hints to guide the user in the process of making the webserver compliant.

    Generation Modules

    The generate_one and generate_many modules are used to generate from scratch configuration files that are compliant with one or more guidelines. Its output consists of a configuration file (for Apache or nginx webservers) that can be directly used to deploy a compliant webserver out-of-the-box.

    Custom Guidelines

    The modules can be customized to take into consideration specific requirements of the user, such as structured custom guidelines or single requirements for selected configurable elements.


    The compliance module can recieve both a configuration file and a hostname/ip as input. If a configuration file is provided the analysis will not check the Certificates since they depend on external files.

Caching system

Each wrapper module includes a caching mechanism. Because it is unlikely that any value would change dramatically in a single runtime, the caching approach allows the program to be less invasive and more powerful (with a runtime usually less than a minute).

Pre-analysis (

As stated before, a pre-analysis (step 3a) is required as a compromise between atomicity, efficiency, and execution speed. Because the testssl startup time is roughly 3 seconds, we need to limit the number of times the tool is called. To do this, the core will determine if the module being run is utilizing as a wrapper, and if so, it will get all testssl-related arguments. Following this, the core will fill the testssl wrapper cache, which will be executed once the analysis is complete.

Demo video

Related Publications

  • Riccardo Germenia, Salvatore Manfredi, Matteo Rizzi, Giada Sciarretta, Alessandro Tomasi, Silvio Ranise
    Automating Compliance for Improving TLS Security Postures: An Assessment of Public Administration Endpoints
    In: 21th International Conference on Security and Cryptography (SECRYPT 2024) (complementary material, news)
  • Matteo Rizzi, Salvatore Manfredi, Giada Sciarretta, Silvio Ranise
    Demo: TLSAssistant v2 - A Modular and Extensible Framework for Securing TLS
    In: Proceedings of the 27th ACM Symposium on Access Control Models and Technologies (SACMAT 2022) (DOI, news)
  • Matteo Rizzi, Salvatore Manfredi, Giada Sciarretta, Silvio Ranise
    A Modular and Extensible Framework for Securing TLS
    In: Proceedings of the Twelfth ACM Conference on Data and Application Security and Privacy (CODASPY 2022) (DOI, news)
  • Salvatore Manfredi, Mariano Ceccato, Giada Sciarretta, Silvio Ranise
    Do Security Reports Meet Usability? - Lessons Learned from Using Actionable Mitigations for Patching TLS Misconfigurations
    In: The 16th International Conference on Availability, Reliability and Security (ARES 2021) (ETACS 2021) (DOI, complementary material, news)
  • Andrea Bisegna, Roberto Carbone, Mariano Ceccato, Salvatore Manfredi, Silvio Ranise, Giada Sciarretta, Alessandro Tomasi, Emanuele Viglianisi
    Automated Assistance to the Security Assessment of API for Financial Services in book Cyber-Physical Threat Intelligence for Critical Infrastructures Security: A Guide to Integrated Cyber-Physical Protection of Modern Critical Infrastructures
    In: Cyber-Physical Threat Intelligence for Critical Infrastructures Security: A Guide to Integrated Cyber-Physical Protection of Modern Critical Infrastructures (DOI)
  • Salvatore Manfredi, Silvio Ranise, Giada Sciarretta, Alessandro Tomasi
    TLSAssistant goes FINSEC: A Security Platform Integration Extending Threat Intelligence Language
    In: 1st International Workshop on Cyber-Physical Security for Critical Infrastructures Protection (CPS4CIP 2020)
  • Salvatore Manfredi, Silvio Ranise, Giada Sciarretta
    TLSAssistant: uno strumento per mitigare i problemi di sicurezza di TLS
    In: ICT Security Magazine (URL, news)
  • Salvatore Manfredi, Silvio Ranise, Giada Sciarretta
    Lost in TLS? No More! Assisted Deployment of Secure TLS Configurations
    In: Proceedings of the 33rd Annual IFIP WG 11.3 Conference on Data and Applications Security and Privacy (DBSec 2019), vol. 11559, pp. 201-220 (DOI, news)

Related Theses

  • Riccardo Germenia (Bachelor's Thesis, University of Trento, 2023)
    A Module to Evaluate the Security Compliance of TLS Deployments: Design and Implementation of a Mechanized Methodology
    Supervisors: Silvio Ranise | Co-supervisors: Salvatore Manfredi, Matteo Rizzi
  • Salvatore Manfredi (PhD Thesis, University of Genoa, 2023)
    Automated Assistance for Actionable Security: Security and Compliance of TLS Configurations (link)
    Supervisor: Silvio Ranise | Co-supervisor: Giada Sciarretta
  • Federico Cucino (Bachelor's Thesis, University of Trento, 2022)
    Miglioramento delle capacità di analisi di TLSAssistant - Automatizzazione delle mitigazioni per NGINX
    Supervisors: Silvio Ranise | Co-supervisors: Salvatore Manfredi, Giada Sciarretta
  • Ivan Valentini (Bachelor's Thesis, University of Trento, 2022)
    Estensione delle capacità di analisi di TLSAssistant - Rilevazione e mitigazione di ALPACA, POODLE e Raccoon
    Supervisors: Silvio Ranise | Co-supervisors: Salvatore Manfredi, Giada Sciarretta
  • Matteo Rizzi (Bachelor's Thesis, University of Trento, 2021)
    TLS Analyzers for Android Apps: State-of-the-art Analysis and Integration in TLSAssistant
    Supervisors: Silvio Ranise | Co-supervisors: Giada Sciarretta, Salvatore Manfredi
    Awards: 3rd place at thesis award "Innovare la sicurezza delle informazioni 2021", sponsored by CLUSIT
  • Salvatore Manfredi (Master's Thesis, University of Trento, 2019)
    Assisting users in securing TLS configurations
    Supervisors: Silvio Ranise | Co-supervisor: Giada Sciarretta

Involved People

Giada Sciarretta

Giada Sciarretta

Matteo Rizzi

Matteo Rizzi

Riccardo Germenia

Riccardo Germenia

Salvatore Manfredi

Salvatore Manfredi

Silvio Ranise

Silvio Ranise