+MASTG-BEST-0043 Enforce Strong TLS Settings When ATS Doesn't Apply (iOS)

MASTG-BEST-0043 Enforce Strong TLS Settings When ATS Doesn't Apply (iOS)

Platform: iOS
Knowledge: MASTG-KNOW-0073

App Transport Security (ATS) only protects connections made through the URL Loading System (URLSession and related Foundation APIs). When your app uses Network.framework, CFNetwork, BSD sockets, or a bundled third-party TLS library, ATS doesn't apply and you're responsible for configuring strong TLS settings explicitly. Apple's documentation states that "ATS doesn't apply to calls your app makes to lower-level networking interfaces like the Network framework or CFNetwork. In these cases, you take responsibility for ensuring the security of the connection." See Preventing Insecure Network Connections.

When possible, prefer URLSession and high-level Foundation APIs so that ATS protections apply automatically. See MASTG-BEST-0042.

Network.framework

Note
Since iOS 26, URLSession and the Network framework now enforce a minimum TLS version of 1.2.

When using NWConnection with TLS, configure NWProtocolTLS.Options and set the minimum TLS version to at least TLS 1.2 using sec_protocol_options_set_min_tls_protocol_version):

let tlsOptions = NWProtocolTLS.Options()
sec_protocol_options_set_min_tls_protocol_version(
    tlsOptions.securityProtocolOptions,
    .TLSv12
)

Embedded Third-Party TLS Libraries

Some apps bundle networking stacks such as OpenSSL, BoringSSL, mbedTLS, or curl that manage TLS independently from any Apple API. Configure them to require TLS 1.2 or later, use strong cipher suites, and enable full certificate chain validation. No OS-level mechanism will catch a misconfiguration in a bundled library. Regularly audit and update bundled libraries to incorporate security fixes.

1. Panoramica

Titolo	Standard

1.1 Riferimenti

1.2 Requisiti identificati

1.3 Regolamentazioni correlate

2. Requisiti identificati

Requisiti
Fonte	Requisito

3. Regolamentazioni correlate

Regolamentazioni
Fonte	Regolamentazione

Ticket collegati

Collegamenti
Tipo di collegamento	Ticket
is related to	MASTG-TEST-0344 Network.framework TLS Protocol Configuration (iOS)
is related to	MASTG-TEST-0345 Embedded or Third-party TLS Stack Configuration (iOS)

OWASP -
EN: Publications of the OWASP Foundation, https://owasp.org/. OWASP® is a registered trademark of the OWASP Foundation, Inc.; GRCA is not affiliated with, nor endorsed by, the OWASP Foundation. Only the versions published by OWASP are authoritative.
- OWASP Application Security Verification Standard (ASVS) 5.0.0, May 2025, from OWASP/ASVS: © 2008-2025 The OWASP Foundation, licensed under CC BY-SA 4.0. Changes: divided into sections and converted into the GRCA format, the wording unchanged. These adaptations are shared under CC BY-SA 4.0 as well.
- OWASP Mobile Application Security Verification Standard (MASVS) v2.1.0, January 2024, from OWASP/masvs: © The OWASP Foundation, licensed under CC BY-SA 4.0. Changes: converted into the GRCA format, the wording unchanged. These adaptations are shared under CC BY-SA 4.0 as well.
- OWASP Mobile Application Security Weakness Enumeration (MASWE) v1.0.0, August 2026, from OWASP/maswe: © The OWASP Foundation, licensed under CC BY-SA 4.0. Changes: converted into the GRCA format, the wording unchanged, linked to the MASVS controls they map to. These adaptations are shared under CC BY-SA 4.0 as well.
- OWASP Mobile Application Security Testing Guide (MASTG) v2.0.0, June 2026, from OWASP/mastg: © The OWASP Foundation, licensed under CC BY-SA 4.0. The tests and best practices only, without code samples, images, tools or apps. Changes: converted into the GRCA format, the wording unchanged; references to other pages of the MASTG as links to mas.owasp.org; the weakness of each test in the numbering of MASWE v1 and linked to it. These adaptations are shared under CC BY-SA 4.0 as well.
- OWASP Software Assurance Maturity Model (SAMM) v2.2.0, July 2026, from owaspsamm/core: © The OWASP Foundation, licensed under CC BY-SA 4.0. Changes: converted into the GRCA format, the wording unchanged; short codes (G-SM-1-A) built from the model, the assessment questions as assessment procedures of their activities. These adaptations are shared under CC BY-SA 4.0 as well.
- OWASP Top 10:2025, from OWASP/Top10: © 2003-2025 The OWASP® Foundation, Inc., licensed under CC BY-SA 4.0. The ten categories, without the icons. Changes: converted into the GRCA format, the wording unchanged. These adaptations are shared under CC BY-SA 4.0 as well. The names of the mapped CWEs (Common Weakness Enumeration): © 2006–2026 The MITRE Corporation. License: The MITRE Corporation hereby grants you a non-exclusive, royalty-free license to use CWE for research, development, and commercial purposes. Any copy you make for such purposes is authorized on the condition that you reproduce MITRE’s copyright designation and this license in any such copy. See the CWE Terms of Use. CWE™ is a trademark of The MITRE Corporation.
DE: Veröffentlichungen der OWASP Foundation, https://owasp.org/. OWASP® ist eine eingetragene Marke der OWASP Foundation, Inc.; GRCA steht in keiner Verbindung zur OWASP Foundation und wird von ihr nicht unterstützt. Maßgeblich sind allein die von OWASP veröffentlichten Fassungen.
- OWASP Application Security Verification Standard (ASVS) 5.0.0, Mai 2025, aus OWASP/ASVS: © 2008-2025 The OWASP Foundation, lizenziert unter CC BY-SA 4.0. Änderungen: in Abschnitte aufgeteilt und in das GRCA-Format umgewandelt, der Wortlaut unverändert. Diese Bearbeitungen stehen ebenfalls unter CC BY-SA 4.0.
- OWASP Mobile Application Security Verification Standard (MASVS) v2.1.0, Januar 2024, aus OWASP/masvs: © The OWASP Foundation, lizenziert unter CC BY-SA 4.0. Änderungen: in das GRCA-Format umgewandelt, der Wortlaut unverändert. Diese Bearbeitungen stehen ebenfalls unter CC BY-SA 4.0.
- OWASP Mobile Application Security Weakness Enumeration (MASWE) v1.0.0, August 2026, aus OWASP/maswe: © The OWASP Foundation, lizenziert unter CC BY-SA 4.0. Änderungen: in das GRCA-Format umgewandelt, der Wortlaut unverändert, mit den MASVS-Controls verknüpft, denen sie zugeordnet sind. Diese Bearbeitungen stehen ebenfalls unter CC BY-SA 4.0.
- OWASP Mobile Application Security Testing Guide (MASTG) v2.0.0, Juni 2026, aus OWASP/mastg: © The OWASP Foundation, lizenziert unter CC BY-SA 4.0. Nur die Tests und Best Practices, ohne Codebeispiele, Bilder, Werkzeuge und Apps. Änderungen: in das GRCA-Format umgewandelt, der Wortlaut unverändert; Verweise auf andere Seiten des MASTG als Links zu mas.owasp.org; die Schwachstelle jedes Tests in der Nummerierung der MASWE v1 und mit ihr verknüpft. Diese Bearbeitungen stehen ebenfalls unter CC BY-SA 4.0.
- OWASP Software Assurance Maturity Model (SAMM) v2.2.0, Juli 2026, aus owaspsamm/core: © The OWASP Foundation, lizenziert unter CC BY-SA 4.0. Änderungen: in das GRCA-Format umgewandelt, der Wortlaut unverändert; Kürzel (G-SM-1-A) aus dem Modell gebildet, die Assessment-Fragen als Prüfverfahren ihrer Aktivitäten. Diese Bearbeitungen stehen ebenfalls unter CC BY-SA 4.0.
- OWASP Top 10:2025, aus OWASP/Top10: © 2003-2025 The OWASP® Foundation, Inc., lizenziert unter CC BY-SA 4.0. Die zehn Kategorien, ohne die Symbole. Änderungen: in das GRCA-Format umgewandelt, der Wortlaut unverändert. Diese Bearbeitungen stehen ebenfalls unter CC BY-SA 4.0. Die Namen der zugeordneten CWEs (Common Weakness Enumeration): © 2006–2026 The MITRE Corporation. MITRE erlaubt die Nutzung für Forschung, Entwicklung und kommerzielle Zwecke, wenn jede Kopie den Urheberrechtsvermerk und die Lizenz enthält; maßgeblich ist der englische Wortlaut der Lizenz oben und die CWE Terms of Use. CWE™ ist eine Marke der MITRE Corporation.