Challenge list
CryptographyLevel 1★☆☆☆☆02. Hidden Secret - Base64 Decode
Base64 is an encoding method used to transmit binary data as text. It's not encryption, but it's often used for…
Network SecurityLevel 1★☆☆☆☆08. Network Basics - Learn Port Numbers
Networks use port numbers to identify services. For example, a web server (HTTP) usually uses port 80, and encrypted…
CryptographyLevel 1★☆☆☆☆11. Decode the Caesar Cipher
The Caesar cipher is one of the oldest classical ciphers used by Julius Caesar. It encrypts by shifting alphabet…
CryptographyLevel 1★☆☆☆☆14. ROT13 Magic
ROT13 (Rotate 13) is a type of Caesar cipher that shifts the alphabet by 13 letters. Interesting feature of ROT13:…
CryptographyLevel 2★★☆☆☆AES-ECB Mode Weakness
ECB leaks repeated block patterns. This introductory task first checks the difference between encryption and encoding.…
CryptographyLevel 2★★☆☆☆RC4 Stream Cipher Weakness
RC4 was once widely used but is now deprecated. This introductory task focuses on recognizing the provided data…
CryptographyLevel 2★★☆☆☆Vigenere Cipher Decryption
Decrypt a Vigenere cipher when the key length is known and retrieve the flag. Ciphertext:…
Network SecurityLevel 2★★☆☆☆Network Analysis - DNS Zone Transfer Leak
An unauthenticated DNS zone transfer (AXFR) against a misconfigured authoritative server was captured. Download the…
Network SecurityLevel 2★★☆☆☆Network Analysis - ICMP Data Exfiltration
Data was exfiltrated from the internal host 10.20.0.15 to the external host 203.0.113.66 disguised as ping (ICMP echo…
Network SecurityLevel 2★★☆☆☆Network Analysis - SMB Share Enumeration Leak
An attacker enumerating SMB shares on the network was captured. Download the packet capture (traffic.pcap), follow the…
Network SecurityLevel 2★★☆☆☆Network Analysis - Telnet Credentials
A legacy server was administered over Telnet in clear text. Download the packet capture (traffic.pcap), follow the…
Network SecurityLevel 2★★☆☆☆Network Analysis - Anonymous FTP Transfer
An anonymous FTP session was captured in clear text. Download the packet capture (traffic.pcap), follow the FTP data…
Network SecurityLevel 2★★☆☆☆Network Analysis - Clear-text HTTP Credentials
Analyze traffic intercepted on public Wi-Fi where someone logged in over plain HTTP. Download the packet capture…
Network SecurityLevel 2★★☆☆☆Network Analysis - Plaintext SMTP Attachment
The internal host 10.30.0.25 sent an email to port 25 of the mail server 10.30.0.10 without encryption. Download…
CryptographyLevel 2★★☆☆☆Finding Hash Collisions
MD5 collisions are practical. Hashes with broken collision resistance must not be used for security-sensitive…
CryptographyLevel 2★★☆☆☆Hash Length Extension Attack
Simple signatures such as hash(secret || message) can be vulnerable to length extension attacks with Merkle-Damgard…
CryptographyLevel 2★★☆☆☆Padding Oracle Basics
Padding oracle attacks use error differences as a plaintext recovery signal. This introductory task decodes leaked…
CryptographyLevel 2★★☆☆☆Rainbow Table Attack
Unsalted fast password hashes can often be reversed with precomputed lookup databases. Reverse the given MD5 hash. MD5…
CryptographyLevel 2★★☆☆☆One-Time Pad Key Reuse Attack
A one-time pad is safe only when the key is used once. Reusing the key lets known plaintext recover other plaintexts.…
CryptographyLevel 2★★☆☆☆Predictable Randomness
Pseudo-random output with a fixed seed is reproducible and must not be used for cryptographic secrets. Flag generation…
CryptographyLevel 2★★☆☆☆Breaking Small RSA Keys
Factor a tiny RSA modulus, recover the private exponent, and decrypt a list of ciphertext values. Public key and…
CryptographyLevel 2★★☆☆☆Cryptanalysis - Breaking the Affine Cipher
ciphertext.txt is an English report encrypted with the affine cipher E(x) = (a*x + b) mod 26. Letter case is preserved…
Network SecurityLevel 3★★★☆☆Network Analysis - 802.1Q VLAN Separated Traffic
capture.pcap was captured from a mirrored switch trunk port, so frames from several VLANs are mixed together with…
Network SecurityLevel 3★★★☆☆Network Analysis - SNMP Information Leak
A device speaking SNMPv2c with a weak community string (public) was captured returning a GetResponse. Download the…