Lack of X.509 TLS certificate validation in OWASP ZAP\n(Zed Attack Proxy)\ncould be used for man-in-the-middle attacks.
\n"}, {"id": "http://www.gabriel.urdhr.fr/2022/02/26/tls1.3-intro/", "title": "Introduction to TLS v1.3", "url": "https://www.gabriel.urdhr.fr/2022/02/26/tls1.3-intro/", "date_published": "2022-02-26T00:00:00+01:00", "date_modified": "2024-11-23T01:15:07+01:00", "tags": ["computer", "web", "network", "tls", "cryptography"], "content_html": "Some notes about how TLS v1.3 works.\nThis is a follow-up of the previous episode\nabout TLS v1.2.\nAs before, the goal is to have a high-level overview\nabout how the protocol works,\nwhat is the role of the different messages\nand be able to understand (and debug) a network traffic dump.
\n"}, {"id": "http://www.gabriel.urdhr.fr/2021/11/30/tls1.2-intro/", "title": "Introduction to TLS v1.2", "url": "https://www.gabriel.urdhr.fr/2021/11/30/tls1.2-intro/", "date_published": "2021-11-30T00:00:00+01:00", "date_modified": "2024-11-23T01:15:07+01:00", "tags": ["computer", "web", "network", "tls", "cryptography"], "content_html": "Some notes\nabout how TLS v1.2\n(Transport Layer Security) works.\nThe goal explain what is going on in a network traffic dump,\nthe role of the different TLS extensions,\nthe impact of the different cipher suites on security, etc.\nIt includes several diagrams and many references.
\n"}, {"id": "http://www.gabriel.urdhr.fr/2021/10/19/diffie-hellman-intro/", "title": "Introduction to the Diffie-Hellman key exchange", "url": "https://www.gabriel.urdhr.fr/2021/10/19/diffie-hellman-intro/", "date_published": "2021-10-19T00:00:00+02:00", "date_modified": "2021-10-19T00:00:00+02:00", "tags": ["computer", "network", "cryptography", "tls", "diffie-hellman"], "content_html": "The Diffie-Hellman (DH) key exchange (and variants thereof) is widely used\nin many protocols\n(such as TLS, SSH, IKE (IPSec), Signal, etc.)\nto bootstrap some symmetric key material\nwhich may then be used to secure communication channel between two parties.\nThis introduction\nfocuses on the different ways the DH key exchange\nis used in practice\nin several protocols (especially TLS)\nand the impact of these different approaches on the security.\nThis is intended as a prelude for the upcoming next episodes\nabout how TLS works.
\n"}, {"id": "http://www.gabriel.urdhr.fr/2021/03/17/frida-disable-certificate-check-on-android/", "title": "Disable certificate verification on Android with Frida", "url": "https://www.gabriel.urdhr.fr/2021/03/17/frida-disable-certificate-check-on-android/", "date_published": "2021-03-17T00:00:00+01:00", "date_modified": "2021-03-17T00:00:00+01:00", "tags": ["computer", "system", "security", "android", "frida", "tls", "reverse-engineering"], "content_html": "Some notes about how to write a Frida script\nwith the (somewhat classic) example of disabling certificate verification\nfor TLS communications on Android applications.
\n"}, {"id": "http://www.gabriel.urdhr.fr/2015/12/09/dns-aggregator-tls/", "title": "DNS aggregation over TLS", "url": "https://www.gabriel.urdhr.fr/2015/12/09/dns-aggregator-tls/", "date_published": "2015-12-09T00:00:00+01:00", "date_modified": "2015-12-09T00:00:00+01:00", "tags": ["computer", "dns", "network", "tls", "privacy"], "content_html": "In a previous\npost, I tried\ndifferent solutions for tunnelling DNS over\nTLS. One of those solutions was\nusing a dedicated DNS-over-UDP fake\nservice replying to all\nqueries with the truncate flag set: this was causing the stub\nresolvers to retry the query using a TCP-based virtual-circuit. This\nsolution is interesting because it is dead simple (it fits in a few\nline of codes) but it is clearly a hack. Here, I am using a dedicated\nDNS forwarder aggregating all\nthe incoming DNS-over-UDP requests over a single persistent TCP\nvirtual-circuit.
\n"}, {"id": "http://www.gabriel.urdhr.fr/2015/02/14/recursive-dns-over-tls-over-tcp-443/", "title": "Recursive DNS over TLS over TCP 443", "url": "https://www.gabriel.urdhr.fr/2015/02/14/recursive-dns-over-tls-over-tcp-443/", "date_published": "2015-02-14T00:00:00+01:00", "date_modified": "2019-12-13T00:53:18+01:00", "tags": ["computer", "network", "dns", "tls", "privacy"], "content_html": "You might want to use an open recursive DNS servers if your ISP's DNS\nserver is lying. However, if your network/ISP is intercepting all DNS\nrequests, a standard open recursive DNS server won't help. You might\nhave more luck by using an alternative port or by forcing the usage of\nTCP (use-vc option in recent versions of glibc) but it might not\nwork. Alternatively, you could want to talk to a (trusted) remote\nrecursive DNS server over secure channel such as TLS: by using DNS\nover TLS over TCP port 443 (the HTTP/TLS port), you should be able to\navoid most filtering between you and the recursive server.