Kirill Firsov (@k_firsov) 's Twitter Profile
Kirill Firsov

@k_firsov

Founder and CEO at FearsOff | Protecting the World’s Top Crypto Exchanges & Financial Institutions | Cybersecurity Enthusiast

ID: 275415930

linkhttps://fearsoff.org calendar_today01-04-2011 06:58:05

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FearsOff Cybersecurity (@fearsoff) 's Twitter Profile Photo

FearsOff has done it again‼️ We’re #1 on Bybit's Top Hackers List—Adding a 5th Major #Exchange to our List of Victories🥇 We're thrilled to announce that our team leader, Kirill Firsov (username firs0v on HackerOne), has claimed the #1 spot on ByBit's Top Hackers List!

FearsOff has done it again‼️ We’re #1 on <a href="/Bybit_Official/">Bybit</a>'s Top Hackers List—Adding a 5th Major #Exchange to our List of Victories🥇

We're thrilled to announce that our team leader, <a href="/k_firsov/">Kirill Firsov</a> (username firs0v on <a href="/Hacker0x01/">HackerOne</a>), has claimed the #1 spot on ByBit's Top Hackers List!
FearsOff Cybersecurity (@fearsoff) 's Twitter Profile Photo

Trusted by the Best: What Our Clients Say About Us 👀 At FearsOff, we value the partnerships we've built with clients across various industries. Their feedback motivates us to continuously innovate and provide top-tier cybersecurity solutions. 📈 But don’t just take our word

Trusted by the Best: What Our Clients Say About Us 👀

At FearsOff, we value the partnerships we've built with clients across various industries. Their feedback motivates us to continuously innovate and provide top-tier cybersecurity solutions. 📈

But don’t just take our word
FearsOff Cybersecurity (@fearsoff) 's Twitter Profile Photo

🚨 Inside the Heist: Russian Hackers Target Crypto Users via Fake Video Apps - Here’s How It Works & What You Need to Know 💥 1/ A recent follow-up on our investigation into fake video conferencing apps revealed that the malicious domain meeten[.]gg is still active, along with

🚨 Inside the Heist: Russian Hackers Target Crypto Users via Fake Video Apps - Here’s How It Works &amp; What You Need to Know 💥

1/ A recent follow-up on our investigation into fake video conferencing apps revealed that the malicious domain meeten[.]gg is still active, along with
FearsOff Cybersecurity (@fearsoff) 's Twitter Profile Photo

Goodbye 2024, Welcome 2025! 🚀 As we step into 2025, we at FearsOff reflect on an incredible year filled with progress and learning. We are deeply grateful for the trust and support of our #partners, clients, team, and community—it’s because of you that we continue to grow and

Goodbye 2024, Welcome 2025! 🚀

As we step into 2025, we at FearsOff reflect on an incredible year filled with progress and learning. We are deeply grateful for the trust and support of our #partners, clients, team, and community—it’s because of you that we continue to grow and
Marwan Hachem (@mar1hachem) 's Twitter Profile Photo

Check out my latest article: 🚨 The Crypto Industry’s Bug Bounty Problem: A Crisis in Valuation and Security Culture 🚨 linkedin.com/pulse/crypto-i… via LinkedIn

Kirill Firsov (@k_firsov) 's Twitter Profile Photo

#bugbountytips Bypass CloudFlare Rate-Limit Ever struggled with CloudFlare rate-limiting when brute-forcing endpoints during your bug bounty research? A simple yet effective bypass is right there in CloudFlare’s documentation — specifically, leveraging the _cfuvid cookie. 1.

#bugbountytips Bypass CloudFlare Rate-Limit

Ever struggled with CloudFlare rate-limiting when brute-forcing endpoints during your bug bounty research?

A simple yet effective bypass is right there in CloudFlare’s documentation — specifically, leveraging the _cfuvid cookie.

1.
FearsOff Cybersecurity (@fearsoff) 's Twitter Profile Photo

🚨 Another Major Milestone Unlocked! 🚨 We’re proud to announce that FearsOff has officially claimed the #1 spot on Upbit Korea Top Hackers leaderboard — and the #1 Most Valued Hacker (MVH) ranking on PatchDay, the platform powering Upbit’s bug bounty program. For context,

🚨 Another Major Milestone Unlocked! 🚨

We’re proud to announce that FearsOff has officially claimed the #1 spot on <a href="/Official_Upbit/">Upbit Korea</a> Top Hackers leaderboard — and the #1 Most Valued Hacker (MVH) ranking on PatchDay, the platform powering Upbit’s bug bounty program.

For context,
Kirill Firsov (@k_firsov) 's Twitter Profile Photo

🥈 Scored the 2nd-highest bounty on HackerOne and broke into the Top 10 leaderboard three times in the past 30 days! Huge thanks to Crypto.com for trusting us with their security—now, back to hunting. 🐛🚀 #BugBounty #EthicalHacking #Cybersecurity

🥈 Scored the 2nd-highest bounty on <a href="/Hacker0x01/">HackerOne</a> and broke into the Top 10 leaderboard three times in the past 30 days! Huge thanks to <a href="/cryptocom/">Crypto.com</a> for trusting us with their security—now, back to hunting. 🐛🚀
#BugBounty #EthicalHacking #Cybersecurity
Marwan Hachem (@mar1hachem) 's Twitter Profile Photo

🚨 Coinbase Breach = Bug Bounty Reality Check 🚨 Yesterday, bribed support agents leaked about 1% of Coinbase 🛡️ users’ personal identifying information (PII). • Criminals demanded $20 M. • Coinbase's CEO Brian Armstrong refused—but matched the demand as a $20M bounty for

🚨 Coinbase Breach = Bug Bounty Reality Check 🚨

Yesterday, bribed support agents leaked about 1% of <a href="/coinbase/">Coinbase 🛡️</a>  users’ personal identifying information (PII).

• Criminals demanded $20 M.
• Coinbase's CEO <a href="/brian_armstrong/">Brian Armstrong</a> refused—but matched the demand as a $20M bounty for
Kirill Firsov (@k_firsov) 's Twitter Profile Photo

The exploit for CVE-2025-49113 is already available for sale on the dark web. I feel sorry for anyone who hasn’t upgraded to the newest version yet. Doomsday is coming, believe me. #roundcube #CVE FearsOff Cybersecurity

The exploit for CVE-2025-49113 is already available for sale on the dark web. I feel sorry for anyone who hasn’t upgraded to the newest version yet. Doomsday is coming, believe me. #roundcube #CVE <a href="/FearsOff/">FearsOff Cybersecurity</a>