TL;DR: This post has a lot of details. Skip to the Summary if you know the challenge and are here just for the solution. Door icon made by Freepik from www.flaticon.com is licensed by CC 3.0 BY. Between Christmas and New Year’s I attended the 35th Chaos Communication Congress (CCC), 35C3, in Leipzig, Germany, together with Malmö based Xil hackerspace. It was my third congress (in a row). Since 2012 there has been a Capture The Flag (CTF) competition at congress.

When working for my employer Sentor I discovered an authentication bypass vulnerability in Auth0. I blogged about it on the company blog: Vulnerability disclosure: Authentication bypass in Auth0

When working for my employer Sentor I discovered a session fixation vulnerability in Auth0. I blogged about it on the company blog: Vulnerability disclosure: Session fixation in Auth0

Last week my favorite IT security podcast Bli säker (Become Secure in English) published the episode The Epochalypse and the QR Code (only in Swedish) where they explained the techonology behind mobile authenticator apps. I felt I needed to refresh my TOTP algorithm support investigation from 2019 before the recording of the next episode of the Bli säker podcast. :) So this is an update to the blog post I published in July 2019 called Many Common Mobile Authenticator Apps Accept QR Codes for Modes They Don’t Support.

You probably use an “authenticator app” such as Google Authenticator to enable two-step verification (sometimes called two-factor authentication, 2FA, or multi-factor authentication, MFA) for an online account. The method is called Time-Based One-Time Password Algorithm (TOTP) and is standardized in RFC 6238. In October 2017 when I evaluated HashiCorp Vault for generating and storing TOTP secrets for a system at work I realized that the Android version and iOS version of Google Authenticator differed a lot when it comes to which modes are supported.

TL;DR: This post has a lot of details. Skip to the Summary if you know the challenge and are here just for the solution. Door icon made by Freepik from www.flaticon.com is licensed by CC 3.0 BY. Between Christmas and New Year’s I attended the 35th Chaos Communication Congress (CCC), 35C3, in Leipzig, Germany, together with Malmö based Xil hackerspace. It was my third congress (in a row). Since 2012 there has been a Capture The Flag (CTF) competition at congress.

When working for my employer Sentor I discovered an origin disclosure vulnerability in Akamai GTM, but they didn’t agree it was a vulnerability. I blogged about it on the company blog: The Akamai origin disclosure non-vulnerability

This is the story on how I discovered that Yubico used an invalid certificate chain in their Personal Identity Verification (PIV) attestation feature on YubiKey 4.3 and YubiKey NEO, which could only be solved by a new hardware release. The impact for users and organizations is that the certificate chain will be deemed invalid by tools that verifies the chain properly, such as OpenSSL version 1.1.0 and later. Yubico has published a custom Python script that can be used to verify their attestation certificate chains.

Do you pentest IoT equipment before joining it to your network? I did, fortunately. I bought a Swedish reader to connect to the P1 port of my electricity meter, and found a number of vulnerabilities that in combination let an attacker “wardriving” outside my house use the P1 reader to join my Wi-Fi network!

So it’s true what they say: the S in IoT stands for Security! ;)

When working for my employer Sentor I discovered an origin disclosure vulnerability in Akamai GTM, but they didn’t agree it was a vulnerability. I blogged about it on the company blog: The Akamai origin disclosure non-vulnerability

When working for my employer Sentor I discovered an authentication bypass vulnerability in Auth0. I blogged about it on the company blog: Vulnerability disclosure: Authentication bypass in Auth0

When working for my employer Sentor I discovered a session fixation vulnerability in Auth0. I blogged about it on the company blog: Vulnerability disclosure: Session fixation in Auth0

During 2021 I had access to a facility equipped with an alarm system from Securitas Direct. I had access as a regular user to Securitas Direct’s My Pages at mypages-pro.securitas-direct.com, which is used to administer some aspects of one’s security alarm installation. That web application suffered a CWE-384 Session Fixation vulnerability which can be used by an attacker in a so-called Man-In-The-Middle (MiTM) position. Home page of Securitas Direct My Pages In summary, if an attacker is on the same network as the victim or somewhere else between the victim and Securitas Direct’s server, and if the attacker can make the victim’s browser make an unencrypted HTTP request to a subdomain of securitas-direct.

I work for the security consultant company Defensify where I conduct security assessments of applications and networks. In December 2020 I made a review of a web application written in Ruby on Rails. I will not disclose the name of the client or any other vulnerabilities found in the client’s application, but this blog post tells the story of how I found a security vulnerability in one of the third-party dependencies they use, which is open source, and got my first ever CVE assigned. \o/

This is a follow-up on the previous post Brute-Forcing Borrowers’ PINs at the Swedish Board of Student Finance (CSN) where I describe some vulnerabilities discovered in August 2020 and the response from CSN. It seems I missed another problem with the CAPTCHA though. And it was right in front of my eyes…

The Swedish Board of Student Finance CSN is the government agency that manages Swedish student finance, i.e. grants and loans for studies. They also manage driving licence loans and home equipment loans. (Source)

This is the story of when I found two security vulnerabilities in their login functionality and reported it to them.

TL;DR: This post has a lot of details. Skip to the Summary if you know the challenge and are here just for the solution. Door icon made by Freepik from www.flaticon.com is licensed by CC 3.0 BY. Between Christmas and New Year’s I attended the 35th Chaos Communication Congress (CCC), 35C3, in Leipzig, Germany, together with Malmö based Xil hackerspace. It was my third congress (in a row). Since 2012 there has been a Capture The Flag (CTF) competition at congress.

I work for the security consultant company Defensify where I conduct security assessments of applications and networks. In December 2020 I made a review of a web application written in Ruby on Rails. I will not disclose the name of the client or any other vulnerabilities found in the client’s application, but this blog post tells the story of how I found a security vulnerability in one of the third-party dependencies they use, which is open source, and got my first ever CVE assigned. \o/

Do you pentest IoT equipment before joining it to your network? I did, fortunately. I bought a Swedish reader to connect to the P1 port of my electricity meter, and found a number of vulnerabilities that in combination let an attacker “wardriving” outside my house use the P1 reader to join my Wi-Fi network!

So it’s true what they say: the S in IoT stands for Security! ;)

This is the story on how I discovered that Yubico used an invalid certificate chain in their Personal Identity Verification (PIV) attestation feature on YubiKey 4.3 and YubiKey NEO, which could only be solved by a new hardware release. The impact for users and organizations is that the certificate chain will be deemed invalid by tools that verifies the chain properly, such as OpenSSL version 1.1.0 and later. Yubico has published a custom Python script that can be used to verify their attestation certificate chains.

When working for my employer Sentor I discovered an origin disclosure vulnerability in Akamai GTM, but they didn’t agree it was a vulnerability. I blogged about it on the company blog: The Akamai origin disclosure non-vulnerability

When working for my employer Sentor I discovered an authentication bypass vulnerability in Auth0. I blogged about it on the company blog: Vulnerability disclosure: Authentication bypass in Auth0

When working for my employer Sentor I discovered a session fixation vulnerability in Auth0. I blogged about it on the company blog: Vulnerability disclosure: Session fixation in Auth0

Last week my favorite IT security podcast Bli säker (Become Secure in English) published the episode The Epochalypse and the QR Code (only in Swedish) where they explained the techonology behind mobile authenticator apps. I felt I needed to refresh my TOTP algorithm support investigation from 2019 before the recording of the next episode of the Bli säker podcast. :) So this is an update to the blog post I published in July 2019 called Many Common Mobile Authenticator Apps Accept QR Codes for Modes They Don’t Support.

You probably use an “authenticator app” such as Google Authenticator to enable two-step verification (sometimes called two-factor authentication, 2FA, or multi-factor authentication, MFA) for an online account. The method is called Time-Based One-Time Password Algorithm (TOTP) and is standardized in RFC 6238. In October 2017 when I evaluated HashiCorp Vault for generating and storing TOTP secrets for a system at work I realized that the Android version and iOS version of Google Authenticator differed a lot when it comes to which modes are supported.

When working for my employer Sentor I discovered an origin disclosure vulnerability in Akamai GTM, but they didn’t agree it was a vulnerability. I blogged about it on the company blog: The Akamai origin disclosure non-vulnerability

Do you pentest IoT equipment before joining it to your network? I did, fortunately. I bought a Swedish reader to connect to the P1 port of my electricity meter, and found a number of vulnerabilities that in combination let an attacker “wardriving” outside my house use the P1 reader to join my Wi-Fi network!

So it’s true what they say: the S in IoT stands for Security! ;)

When working for my employer Sentor I discovered an origin disclosure vulnerability in Akamai GTM, but they didn’t agree it was a vulnerability. I blogged about it on the company blog: The Akamai origin disclosure non-vulnerability

When working for my employer Sentor I discovered an authentication bypass vulnerability in Auth0. I blogged about it on the company blog: Vulnerability disclosure: Authentication bypass in Auth0

When working for my employer Sentor I discovered a session fixation vulnerability in Auth0. I blogged about it on the company blog: Vulnerability disclosure: Session fixation in Auth0

During 2021 I had access to a facility equipped with an alarm system from Securitas Direct. I had access as a regular user to Securitas Direct’s My Pages at mypages-pro.securitas-direct.com, which is used to administer some aspects of one’s security alarm installation. That web application suffered a CWE-384 Session Fixation vulnerability which can be used by an attacker in a so-called Man-In-The-Middle (MiTM) position. Home page of Securitas Direct My Pages In summary, if an attacker is on the same network as the victim or somewhere else between the victim and Securitas Direct’s server, and if the attacker can make the victim’s browser make an unencrypted HTTP request to a subdomain of securitas-direct.

I work for the security consultant company Defensify where I conduct security assessments of applications and networks. In December 2020 I made a review of a web application written in Ruby on Rails. I will not disclose the name of the client or any other vulnerabilities found in the client’s application, but this blog post tells the story of how I found a security vulnerability in one of the third-party dependencies they use, which is open source, and got my first ever CVE assigned. \o/

This is a follow-up on the previous post Brute-Forcing Borrowers’ PINs at the Swedish Board of Student Finance (CSN) where I describe some vulnerabilities discovered in August 2020 and the response from CSN. It seems I missed another problem with the CAPTCHA though. And it was right in front of my eyes…

The Swedish Board of Student Finance CSN is the government agency that manages Swedish student finance, i.e. grants and loans for studies. They also manage driving licence loans and home equipment loans. (Source)

This is the story of when I found two security vulnerabilities in their login functionality and reported it to them.