ZeroDisclo.com is a non-partisan non-profit platform. It enables vulnerability reporting while maintaining anonymity for the discoverer. It’s got a spring refresh to make it even easier to do vulnerability disclosure right.

 enables vulnerability reporting while maintaining anonymity for the discoverer. Thus, ZeroDisclo channels an insightful disclosure process all by protecting the vulnerability reporter and providing timely and detailed information to the receiving 

ZeroDisclo builds the bridge between an ethical hacker and a CERT. The platform formalises the report through various criteria enabling the calculation of a CVSS severity score. Even more important, thanks to the report’s encryption with the keys of the person submitting the report and of the receiving organisation, ZeroDisclo serves as a ‘transmission belt’. At no time does the platform or the individuals administering it access the details of the vulnerability described.

ZeroDisclo is also available as a .onion instance, enabling coordinated vulnerability disclosure 

. Regardless of the web browser the submitter uses, the report is encrypted with the receiving organisation’s public key, then signed and timestamped by a blockchain. The site sends the report to a CERT; the vulnerability discoverer receives a certificate as proof of deposit. Coordinated vulnerability disclosure is thus possible without ZeroDisclo having to accumulate a dangerous knowledge of the bugs affecting third-party information systems.

NEW TO COORDINATED VULNERABILITY DISCLOSURE?

WE’VE GOT YOU COVERED: READ OUR WHITE PAPER.

Enabling coordinated vulnerability disclosure is essential. ZeroDisclo is a uniquely positioned tool that does just that. The technology behind it does disclosure well.

That is why we deem it necessary also to give the website a spring refresh. The redesigned-from-head-to-toe website aims at seamless navigation—vulnerability disclosure is also done right when it is done through an unambiguous interface. Among other things, the submission form now indicates what parts of the vulnerability report are encrypted. Furthermore, the FAQ provides answers to many questions we have received since the platform’s inception in late 2016.

Indicate which report details are concealed

We heavily insist on the importance of bringing sensitive information to the right people without exposing the discoverer to unnecessary legal danger in the process. Alongside, we need not receive a copy of those details: our work aims to contribute to reducing vulnerabilities, not to stockpile them.

The vulnerability submission form is a central tool on ZeroDisclo. As it enables the discoverer to reach out to the receiving CERT, we have paid particular attention to make it as unambiguous as possible. Hence the little icon that indicates which parts we have access to—and which we do not.

A FAQ to better know what you can(not) do with ZeroDisclo

You have questions; we get that. And get these, too ? Hence a FAQ to reflect the various questions we have received in the past nearly-four years. The page is accessible through the top navigation menu. The questions are under broader 

, clarifying aspects for the different roles that partake in the vulnerability disclosure process.

CERT onboarding and further awareness raising

On the other side of ZeroDisclo’s ‘transmission belt’ is a CERT.

A short yet unambiguous Disclosure Policy

The CERT needs time to investigate. Reproducing the vulnerability may take time; cascading details to all concerned parties and organising fixes is also time-consuming. That is the reason we have outlined a concise yet straightforward Disclosure Policy. Acknowledging it is the final and mandatory step before submitting the vulnerability report.

An infographic to grasp ZeroDisclo in the blink of an eye

We aim for ZeroDisclo to be effortless to use. Yet, there will always be newcomers, both in the hacker community and within CERTs. Hence a dedicated ‘How it works’ page—and infographic has the spotlight therein. We have given it 

 approach, adding a more detailed step-by-step explanation at the bottom of the page.

In the coming 48 hours, we will provide a full infographic to the CERTs listed on ZeroDisclo. We aim it as a handy tool they can use internally to raise awareness about vulnerability disclosure done right. Until then, make the Internet safer—use ZeroDisclo.com!

ZeroDisclo.com: Vulnerability disclosure done right

, we sat down with the Information System Security Expert of a major European financial institution. Read on to learn how a heavily regulated industry implemented Bug Bounty.

Why did you decide to launch a Bug Bounty program?

To be honest, I wasn’t convinced at first. I imagined it was a ‘patchwork’ of various missions being carried out by their pentesters and not an established, focused activity.

 team who pre­sented different advantages that met my security expectations. Following this, we launched an initial 

 campaign on a site we knew well and which we had already tested multiple times before. Choosing a mature scope enabled me to control the potential program costs.

I wasn’t expecting to get any feedback as we were already on our eighth penetration test on the site since I’d been on the job. And the last test had been conducted just the week before. 

But the results proved us wrong: we received multiple vulnerability reports, including one that was critical, just an hour after launching the program

. We now know this vulnerability had existed for 18 months. In other words, 

two pentests had taken place without it being noticed. So, Bug Bounty instantly appealed to us! (Laughs)

What value does Bug Bounty offer compared with traditional cybersecurity solutions, such as penetration testing?

First, you’re getting something close to the real thing. By that I mean we’re not trying to get a comprehensive view of the vulnerabilities. We’re trying to hit right where it hurts immediately. That’s very close to what a real attack would do.

Second, Bug Bounty gives us continuity – vital given the current agility trend. We continually update our internet applications (at least once a month); so, it becomes complicated and costly to pentest each deployment. Bug Bounty enables us to monitor continuously.

Third, the efficiency and quality of the work done by the hunters is exceptional. On sites that we’d tested multiple times, we systematically found vulnerabilities, some of which were critical. The hunters are paid based on results, so their goal is to find something concrete for us – and that’s my goal, too. One of the problems with pentesting is that the results rely entirely on the pentester.

With Bug Bounty, we work with specialists. The hunters won’t necessarily look for every type of vulnerability that may exist on a web application. Instead, they go where they perform the best – and where they can be swift and effective. That’s what we’re looking for, too.

Since we launched our Bug Bounty program, we’ve upped our security game: we found new vulnerabilities. We were able to fix them, and the security of these applications is now a cut above. Ultimately, that’s what a CISO should be aiming for: not just compliance, but enhanced security.

The final very important advantage is the return on investment (ROI). Between the reward budget and the cost of the platform – and given the results – over the year, it’s very profitable. I have twice as many vulnerabilities reported via my Bug Bounty program than I did with pentesting, and it costs me about 50% less.

I’ve been pentesting critical sites for years and getting empty or nearly empty reports in return. We were paying because it was our policy, and we needed to meet our compliance requirements; but it brought us nothing, or almost nothing more, in terms of security.

Does Bug Bounty mean the end of penetration testing, or are the two complementary?

They’re still complimentary, but it will reduce the perimeter seriously. We will aim to maintain the same number of pentests, but focus them on less critical areas.

I’m now wondering if it makes any sense to do annual pentests on applications managed in agile mode. And for all the critical web-based applications, we’re moving towards full Bug Bounty.

How does Bug Bounty work in your company? Have you observed any changes in your teams since you began Bug Bounty?

We’re in a ‘managed’ program, meaning we don’t do the vulnerability triage ourselves. But, internally, I’m in charge of overseeing the Bug Bounty program. It’s a little time-consuming at first; you need the discipline to avoid looking at every vulnerability, one by one, as soon as you get them. Once you es­tablish your rhythm (for me, that’s once a week), it’s advantageous. Speaking of time, it’s close to that of managing a classic pentest. On the other hand, it’s a lot simpler to launch and monitor than a pentest.

We gave the Operational Security team direct ac­cess to our program. This way, our colleagues can see the vulnerabilities as soon as they’re validated. Also, our developers can interact directly with the hunters. We’ve involved them right from the launch of the project, so, they didn’t take it as a ‘punishment’, but rather like a game of offence/defence. That’s exactly how I wanted it to work; it was like: ‘Oh, they’re good, how do they do that?’. (Laughs)

Engaging with the developers has made us a lot more effective. It helps them improve and, in general, helps us make progress in terms of security.

We were aware that we needed to change. However, we couldn’t address the need for checking production applications by performing pentests (monthly roll-outs). In essence, we were in the process of deploying without really respecting our security policy because we could only audit them over time. Therefore, we needed to find another solution, and that solution was Bug Bounty.

I do believe Bug Bounty is designed for agility.

We can’t be agile when we’re doing pentests. There are just too many projects to follow, and we can’t do one before each roll-out owing to the lack of time, responsiveness, and means. The deadlines are too tight, continually shifting, and the tests have to be scheduled several times a year.

Bug Bounty has ultimately allowed us to launch a real monitoring process for DevSecOps. Moreover, we can provide agile, in-depth security in collaboration with all stakehol­ders without overly impacting them, with continuous improvement in mind.

For example, when a vulnerability is reported, validated, and sent for processing, we’re told internally that the application firewall has been updated as a result. Then, we ask the hunters to check—and they always manage to exploit the vulnerability by going around the web application firewall (WAF) another way. This interplay is continuous improvement in action and reveals that the code must be fixed. If necessary, we can put the hunters and developers in contact, to further discuss the vulnerability and its fix.

Everyone is empowered, equipped, and a lot more responsive – that’s the beauty of DevSecOps.

If you want more informations about Bug Bounty & YesWeHack, 

Founded in 2013, YesWeHack is the #1 European Bug Bounty & VDP Platform.

YesWeHack offers companies an innovative approach to cybersecurity with Bug Bounty (pay-per-vulnerability discovered), connecting tens of thousands cyber-security experts (ethical hackers) across 120 countries with organisations to secure their exposed scopes and reporting vulnerabilities in their websites, mobile apps, infrastructure and connected devices.

YesWeHack runs private (invitation based only) programs, public programs and vulnerability disclosure policies (VDP) for hundreds of organisations worldwide in compliance with the strictest European regulations.

How a heavily regulated financial institution implemented Bug Bounty

YesWeHackEDU, a fully-fledged educational platform, mobilises real-world hacking techniques for training purposes. YesWeHackEDU provides a reliable approach for reporting vulnerabilities and is a tangible evaluation tool. The platform offers free subscriptions for two months starting from 1 April to help universities during the COVID19 outbreak.

Through getting together ethical hackers (‘bug hunters’), and organisations committed to improving their cybersecurity, bug bounty platforms play an essential role in implementing coordinated vulnerability disclosure and surfacing bugs to reduce cyber risk.

Cybersecurity is both an economic and societal issue. Yet, this sector suffers from an imbalance between the state of the threat and the market’s defence capabilities. Thus, the capacity of public and private actors to detect and correct shortcomings professionally and ethically must be rapidly strengthened. To remedy that imbalance, we need comprehensive training and better information sharing.

 in November 2019, a unique and fully-fledged educational platform aimed at students and teaching crew alike. Due to the current 

, we have decided to provide basic two-month free licences to learners and instructors, enabling skill-building to continue despite the pandemic.

 self-education: complementary yet insufficient

Although more and more universities and training initiatives sprawl, they are unlikely to mitigate the growing skills shortage. Formal cybersecurity education is unable to replenish the talent pool at a pace that follows the increasing complexity of cybersecurity challenges. In contrast, an overwhelming majority of ethical hackers operating today are self-taught. Self-education is possible thanks to abundant online resources and expanding events which increasingly feature a Capture-the-Flag (CTF) type of activities.

Both formal education and self-training have shortcomings. University curricula remain too theoretical, students setting foot in real-world operations solely during their internship. The latter often happens at the Bachelor or Master’s level. Pluridisciplinarity is still challenging to achieve, a hurdle especially damaging to cybersecurity and computer science curricula.

Self-education, on the other side, relies on the individual’s commitment and ability to identify security-focused courses available and select the ones most relevant to the issue at hand. Even with a performant self-directed learning resource set at hand, 

 in online education, albeit their role becomes one of a learning catalyst and knowledge navigator.

The broader connected society understands the challenge. The outcome is new education tools for security, aiming to solve the cybersecurity skills gap through an approach outside the classroom. Both free and paid-for coursework designed by ethical hackers features amongst those tools, all encouraging and relying on collaboration into the cybersecurity community.

The bug bounty platforms all have a dedicated “Resources” page. A closer examination of these pages, however, concludes to a high uniformity of available content.

YesWeHackEDU builds bridges between universities and communities

Bug bounty programs include concrete incentive structures and processes designed to encourage individuals with a range of experience and talent to identify and report potential security vulnerabilities. Embracing this idea requires a real sense of agency on the individuals. Yet, relying on the person alone is short-sighted at best. Collaboration through practical situation awareness thus leverages an innovative way for formal education to keep up with the rapidly evolving talent need landscape.

 is a unique and fully-fledged educational platform in both its approach and outreach. It mobilises real-world data in a structured way. Alongside diverse training environments matching different student levels, YesWeHackEDU provides a reliable methodological approach to vulnerability report composition and constitutes a tangible evaluation tool.

Academia needs to capitalise on the available online tools for teaching and welcome innovative approaches to training. YesWeHackEDU is one such progressive development. Three main educational scenarios made possible by YesWeHackEDU: as part of a cybersecurity curriculum; as a module for Computer Science curricula more broadly (e.g. software development, data science); as part of life-long learning programs.

YesWeHackEDU as part of a formal cybersecurity curriculum

Crowdsourced security invests organisations with the skills, experience and nonstop coverage of creative and experienced security researchers. These hunters work to identify vulnerabilities before criminals exploit them. Such a proven model for crowdsourcing the right expertise, applying it when and where need be, and rewarding for results is what YesWeHackEDU enables in the classroom.

Through engaging students and the teaching crew with the training environment, YesWeHackEDU offers a blended learning approach for cybersecurity curricula. The educational set-up streamlines learning effectiveness in building upon students’ pre-existing technical knowledge and fostering their proactivity, autonomy and rigour. Since YesWeHackEDU reliably tracks contributions, teachers can follow progress and grade based on a formal and harmonious delivery process.

The ongoing COVID19 outbreak has drawn learners and teachers away from the classroom. Still, cybercriminals are riding the pandemic wave, often adding a cyber crisis to the health crisis. 

’s mission to build bridges between ethical hackers and organisations, we have decided to provide free licences to any university, starting 1 April. Those licences span two months.

They will enable teachers and students alike to benefit from top-notch pedagogical resources during the COVID19 pandemic.

YesWeHackEDU: Addressing talent shortage through Bug Bounty

Why did you implement a bug bounty program?

We’ve been ISO 27001 certified since 2014 and are mandated to use penetration testing to seek out vulnerabilities. At first, the penetration testing proved useful. Over time however, they produced fewer exciting outcomes. We quickly realised that owing to the limited duration of an audit (2-3 weeks), the penetration tester didn’t have the time to identify more severe vulnerabilities. At best, he or she had hunches, but then we needed to work on them.

 had been working well in the U.S. Household name brands were using the approach.

We explored red team and bug bounty, with researchers coming from diverse backgrounds to test our scopes and discover new vulnerabilities.

If we’d gone with red team, we’d have encountered the same problem we had with the classic penetration testing I mentioned before. So, we chose to launch a bug bounty in the belief that, although the penetration testers were no longer finding anything, that didn’t mean there weren’t other problems.

We started with a private program collaborating with approximately 15 hunters because we weren’t ‘sure’ about our applications. The hunters identified some significant vulnerabilities. We gradually invited more hunters before finally going public with two scopes: our infrastructure service and our customer portal.

Can you describe the evolution and development of your program?

It was reasonably quick – one year – to implement the program. When we went public, we didn’t experience a sharp spike in vulnerabilities: we started with a grid of very reasonable bonuses, which we gradually increased to reactivate hunter activity on our program to reach our current ‘cruising speed’.

Did sovereignty influence your decision to work with YesWeHack?

Yes, definitely. When we considered bug bounty, we were aiming for both the 

 certification. It therefore seemed more opportune for us to work with a French partner, giving us solid guarantees on how our data is managed.

Is working with a sovereign platform an asset for you in the way you approach your market?

Yes, the concept of sovereignty is essential to our French and European customers. Those include public and para-public organisations, as well as organisations of strategic importance (

OIV or Operators of Vital Importance; abbreviated as per its French naming

), that are sensitive to the issues of sovereignty and control of their data. In the context of cloud services provisioning, partnering with a sovereign platform like 

 assures our customers that the end-to-end vulnerabilities processing chain is controlled effectively.

 a competitive advantage because it guarantees active security: where we once performed biannual penetration testing and periodic scans, we’re now looking for vulnerabilities continuously. The moment a hunter signals a vulnerability, we’re able to include it in our correction cycle automatically. Our customers are reassured, knowing that we don’t wait for updates from vendors to fix our vulnerabilities. Also, we’re able to detect and fix vulnerabilities in our products we develop in-house.

First, hunters don’t face any time constraints. They can take the time they need to detect sophisticated vulnerabilities, further develop an exploit, suggest remediation, and write up a detailed report. By contrast, penetration testing often results in a few scans and two or three CVEs, without any concrete proof of exploitations.

The diversity of the community is another advantage: I can exchange with hunters specialising in UI, for example, and others in application services. Each of them offers different, complicated things that a ‘non-specialised’ auditor could never find. Sometimes, I think you have to be crazy to notice stuff like that!

I have access to a wealth of expertise. They find things that no-one else could.

My team are familiar with different approaches, through talking to people with different approaches to vulnerability management. We sometimes have to explain that a finding isn’t a vulnerability, but rather a misuse at their end and so on.

Last but not least, a bond builds up over time with individual hunters. If a researcher has found significant vulnerabilities, and he or she wants to test more complex things, then we give them the resources or access to do more exciting stuff. This in-depth, collaborative approach is impossible to achieve with penetration testers who are consistently overwhelmed and caught up with their tight deadlines.

Do bug bounty programs spell the end of penetration testing? Or will they remain complementary?

In my opinion, they are two completely approaches: I use penetration testing for their certifying value and to comply with specific standards, which allows me to satisfy customers requiring these certifications. Meanwhile, bug bounty meets the need for more operational security and to focus on all the things that penetration testing and classic scans aren’t able to detect.

Have you seen any changes in your teams since Outscale began using bug bounty?

At the SOC (security operations centre), we manage the existing programs, bonuses, and relationships with the hunters, the creation of new programs, and any changes in the scopes. The bug bounty reports come to my SOC team, which then qualifies each vulnerability.

In 90 percent of cases, they are non-critical vulnerabilities that are quickly qualified. If there is any doubt, we discuss it in-house. If the vulnerability is particularly interesting, the person in charge of managing it presents it to the team. We then talk about its potential impact, the solutions we can use, the hunter’s recommendations, and how we can ensure it doesn’t come up again. These exchanges increase the skills of the entire team.

Does this also mean your teams collaborate more closely?

Yes, because it stimulates curiosity; people are interested and want to understand. It’s always more concrete to show a real vulnerability that has taken place on the platform.

Are your teams and the organisation more agile?

We work in continuous integration, and bug bounty lent itself to our agile methods.

When we receive a vulnerability report, we qualify the CVSS score and, based on that score, we determine the remediation deadline. The report is then sent directly to the relevant teams for correction. The same applies to the dependencies used in the code; they’re sent to R&D for analysis and version upgrade. In every case, bug bounty is an entry point like any other, and as such, vulnerabilities are managed via tickets.

We adapt the processing according to the urgency: if a rapid correction is required, we deliver a patch immediately, to be reinstated in the next version. In this case, we create (or modify) a user story using these new elements, which will serve as a basis for developments.

We will expand our scopes in the programs. We will also encourage hunters to ‘go deep’ inside our product (beyond the web-based front-end). And we will increase the bonus grid.

I’d also like to give them access to our private platforms so they can perform more stringent tests. We’ve already tried this once, and it produced insightful results, with hard-coded data extraction scenarios, on our test platforms. However, this involves giving hunters specific testing scopes, which is time-consuming.

Founded in 2015, YesWeHack is the #1 European Bug Bounty & VDP Platform.

YesWeHack offers companies an innovative approach to cybersecurity with Bug Bounty (pay-per-vulnerability discovered), connecting tens of thousands cybersecurity experts (ethical hackers) across 170 countries with organisations to secure their exposed scopes and reporting vulnerabilities in their websites, mobile apps, infrastructure and connected devices.

YesWeHack runs private (invitation based only) programs and public programs for hundreds of organisations worldwide in compliance with the strictest European regulations.

 (VDP), a learning platform for ethical hackers called 

 and a training platform for educational institutions, 

How Outscale secures its sovereign cloud with YesWeHack

 was rather tricky: you needed to solve an obfuscated XPath request to derive working serials

. The 3 first hunters to solve this challenge are rewarded a prestigious 

 geared towards learning bug exploitation the fun and visual way.

The DOJO is three things in one: a learning tool, training platform and a playground.

The DOJO is the arena where the 4th challenge took place (see the 

We are glad to announce the #4 DOJO Challenge winners list.

 feeds to be notified of the upcoming challenges.

Read on to find the best write-up as well as the challenge author’s recommendations. For this instalment of the DOJO Challenges, we have selected two write-ups as their approaches are distinct and rely on different tools. Read on then!

You have to find the seven valid serials returning the Access granted! string from the XPath query. The $serial input is filtered to restrict the input to the use of digits and hyphen (-) and 19 characters. The serials format is given: xxxx-xxxx-xxxx-xxxx where x is a single digit.

Tricky tricky… there was a hint pointing us to 

, but is that challenge even human-solvable?

We also asked you to produce a qualified write-up report explaining the logic allowing such exploitation. This write-up serves two purposes:

Determine the contestant ability to properly describe a vulnerability and its vectors inside a professionally redacted report. This capacity gives us invaluable hints on your own, unique, talent as a bug hunter.

solve the challenge without the use of any tool

The second valid report is a piece of mastery crafted by 

We were absolutely thrilled by the quality of this session’s reports.

During the testing, I found that we need to find seven valid serials for the provided XPATH query. The format of a serial is defined as: 0000-0000-0000-0000. There are filters applied on the provided serial:

A serial can only contain 0-9 numbers and ‘-‘ character. If any other character is provided, then it will be replaced by ‘0’

I solved this challenge by writing a constraint solver using Z3 theorem prover tool.

 The code is obfuscated and unreadable for me. So I took apart the query in different portions. This way I could easily read the XPATH query and understand it. See below:

 Now, I tried to solve the equations that do not contain the $serial value, by passing the XPATH query in template parameter to endpoint /backend/xpath as shown in the image below:

 Thus, I have solved all the possible equations and put it in the image shown in Step 1 above. It now goes like this:

So, we have minified the XPATH query. Please note the lines 21 and 23 in the image in Step 3:

The line 21 with value 1 is the second argument of first substring function which indicates the starting index of string.

The line 23 indicates the length of that string which is 15.

As we can see, the length of “Access granted!” is same as the length of “Access refused!”, and both equal to 15.

 Now, note the second substring function which takes the output of translate()*42 as its second argument and 15 as third argument. We can thus understand that, if we want to get the “Access granted!” string, then the output of translate()*42 should not be greater than 15.

. substring("abcdefghijklmno", 16 ,15) will output nothing as second argument (

starting of the string) as it is greater than the length of the string.

 Another thing to observe is the arguments of the translate function. We can think of translate as a replace function which does not follow any order.

 translate('abc', 'cb', 'YX') will output aXY 

 ‘c’ is replaced by ‘Y’ and ‘b’ is replaced by ‘X’, although they were in different order.

In our minified XPATH query, we could see the second argument of translate function is uareltsf and the third argument is 01001011. And the conditions (

) from line 3 to 17 eithers outputs true or false. So, this means true will be replaced by 0000 and false will be replaced by 11110.

To fufill the condition in Step 5 above, we need all the values equal to true since after concatenation it will output truetruetrue.... which will be replaced 0000000000.... and Access granted! will be printed out.

However, to realise those conditions, we need to write a constraint solver. I wrote a small script using Z3 to solve it. I have also added comments in the code to make it more self-explanatory.

Requirements: Follow the instructions here:

Run the provided solution script using python: python sol.py

I found the following 7 valid serial keys:

BONUS: MARCOSEN manual solve (well, if brain had fingers)

The problem here is, that only some obfuscated code is used to hide the evaluation of the serial.

The first part was to remove all the “static garbage” from the code. This means to evaluate all the terms that do not contain the serial. I did this by just sending the term I wanted to evaluate and checking the servers answer.

The next step was to replace all the substring-methods just to make it obvious which part of the serial should be evaluate in that part of the code. I replaced it in the code-snippet below with partX.

Looking at the substring with “granted”, we can observe that the translate-method must be 0, so that we get the substring of the beginning of “granted”. These leaves us with the information that the concatenation of the inner terms must be as follows:

For the math, I will replace part1-part4 with a-d. Simplifying the terms gives us seven equations:

Time to solve the equations! I started by just making it all depending on c. This gives us:

Ok, so c = ? How do we get the value of c? We know that c must be dividable by 9. It must also be dividable by 4, because b = c/4. Also b must be dividable by 5. So, we need the least common multiple (LCM) of 5, 9 and 4. This gives us that c must be a multiple of 180. So, for the next steps I will express this with c = 180x.

But that’s not the end of it. The next step was the hardest for me. It’s the step to get the equation for d to be true. By using the multiplicative inverse modulo of 8 we can get the correct values for c:

This gives us the values of x and therefore the seven values for c = 180x. With the equations above the input strings for the admin access are:

 is the Technical Ambassador at Yes We Hack. He also created the DOJO and this challenge.

While Z3 was not required to solve this challenge, it is a nice simple exercice to get started with the library. Z3 or other SMT solver can be really useful when dealing with a large number of constraints.

DOJO CHALLENGE #4 Winners!

Every business needs a vulnerability disclosure policy. Thankfully, a growing number of organisations have one. Yet, those programs are not always a click away. Here’s to a unique plugin for both Chrome and Firefox, because making it easy to report issues need not be much work.

We are all too familiar with the quotidian data breach debacle that organisations go through more often than not. Besides, the initial notice frequently comes from an “anonymous report” or a disgruntled ethical hacker tweeting about your mishandling their repeated vulnerability notifications.

Those are situations we observe, yet many still struggle with preparing for them and the PR mess that inevitably follows. Shooting the messager, coming up with statements that look pretty much like they have been 

 for months, are all symptoms that you are ill-prepared to handle reports from the broader security community.

One robust approach to preventing stinky headlines and loss of trust from customers and partners is a vulnerability disclosure policy (VDP). That policy is a commitment that your organisation will receive, evaluate, and if need be, fix vulnerabilities notified by security folks external to the business.
A VDP also clarifies that you will not go after ethical hackers willing to help you improve the security of your service or product.

For a VDP to be efficient, it needs a few essential elements:

 clearly state what is what, identifying assets that your VDP covers.

 specifically directed at ethical hackers, this bit confirms your commitment to not prosecuting well-intentioned researchers who report a vulnerability. That part is particularly important as legal clarity across organisations and countries is extremely challenging to achieve.

: the precise mechanism your organisation has set up and, ideally, the details you would want to see added to a vulnerability report. The aim here is to make said report the most useful possible to the organisation’s technical team.

: anything you find relevant to smoothen communication.

You get it right: setting up such a policy implies you have thought out roles and responsibilities internally. Rather than a burden, setting a VDP and organising it is a way of developing talent, breaking silos and improving security altogether.

The better news: Showcasing your VDP has never been easier

You have a VDP; you need to feature it prominently on the organisation’s website so it is accessible to anyone who needs it. One way of doing so is creating a dedicated webpage, 

Another way is thanks to a simple tool that comes in handy, namely 

. You fill in the form, download the file and upload it to the business’s website. Your security.txt can contain 

. Indeed, a Bug Bounty programme is a vulnerability disclosure policy with a monetary reward system.

Whichever way you choose, you will want it to be known. Well, now, 

 . Whenever you browse the web, the plugin indicates whether a VDP exists. Because making it easy to report issues does not need to be much work!

Wanna go for a cool – and secure – carpooling service?


We have marked cases where a VDP exists without a security.txt as “room for improvement” to highlight that security.txt is a (draft, for now) standard. As such, it makes locating a VDP policy even easier since one needs no extra browsing to find the contact detail: the security.txt file is always present at www.mywebsite.tld/.well-known/security.txt

Showcasing your vulnerability disclosure policy to the world

Interview with Romain Lods, Head of Engineering,

About two years before we launched our Bug Bounty program, we started internal security audits on our code, which had never been done before at Deezer. These tests allowed us to make a first pass and fix some obvious vulnerabilities.

Then we became interested in Bug Bounty and 

The ease of use of the platform convinced us of launching a program.

 Following the launch, we very quickly received interesting vulnerabilities, everything went smoothly, so we decided to conti­nue and expand our perimeters.

The YesWeHack Blog

ZeroDisclo.com: Vulnerability disclosure done right

How a heavily regulated financial institution implemented Bug Bounty

YesWeHackEDU: Addressing talent shortage through Bug Bounty

ZeroDisclo.com: Vulnerability disclosure done right

How Outscale secures its sovereign cloud with YesWeHack

DOJO CHALLENGE #4 Winners!

Showcasing your vulnerability disclosure policy to the world

How Outscale secures its sovereign cloud with YesWeHack

Deezer protects their artists & users with a public Bug Bounty program

BlaBlaCar leverages crowdsourced security to secure its millions of users’ data

YESWEHACK PROPHILE ON EBODA

Deezer protects their artists & users with a public Bug Bounty program

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