The challenge is called Vampire, which causes association blood.There is also this gif in the website:
![](https://i.imgur.com/B3Anj4u.pnghttp://)
Those two made me imeddiatly think about heartbleed, also the website has a self signed certificate so it's also suspicious.I have used metasploit to try and check if it's actually vulnerable to heartbleed and it is:![](https://i.imgur.com/SDwp9Vw.png)
Now i can run the exploit script serveral times to leak some data:![](https://i.imgur.com/2UI6IzF.png)
Now the website had a login page, so i decided to grep the leaked data for username and got the flag:![](https://i.imgur.com/JldvVxW.png)
Flag:```BSidesTLV2020{Bl00d_Bl00d_Bl00d!!!}```