Challenge list
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…
LinuxLevel 3★★★☆☆Linux-Capabilities. Privilege Escalation Beyond SUID
A specific binary on this system has Linux capabilities assigned to it. Investigate a privilege escalation technique…
LinuxLevel 3★★★☆☆Linux-SUID Exploit. Escalating Privileges via the find Binary
A copy of the find command with the SUID bit set exists on this system. Use a well-known GTFOBins technique to obtain…
LinuxLevel 3★★★☆☆Linux-Proc Memory. Peeking at a Process's Environment
A daemon process runs continuously in the background, with the flag set as one of its environment variables.…
LinuxLevel 3★★★☆☆Linux-Strace. Tracing System Calls to Expose a File
A binary that leaves nothing in standard output or on disk is provided. It reads a key from a hidden file,…
LinuxLevel 3★★★☆☆Linux-Race Condition. Exploiting a TOCTOU Gap for Root Files
A cleanup script that root runs periodically has a gap (TOCTOU) between checking and acting on a file. Try exploiting…
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…
Network SecurityLevel 3★★★☆☆Network Analysis - SSL Strip Clear-text Credentials
An SSL Strip attack downgraded HTTPS to HTTP, so the victim's credentials traveled in clear text and were captured.…
Network SecurityLevel 3★★★☆☆Network Analysis - Unmasking WebSocket Frames
capture.pcap records WebSocket traffic between a browser and a chat server. Every client-to-server frame is masked…
Network SecurityLevel 3★★★☆☆Network Analysis - Custom Protocol Decoding
Traffic from a system using a small custom binary protocol was captured. Download the packet capture (traffic.pcap),…
CryptographyLevel 3★★★☆☆Cryptanalysis - RSA Common Modulus Attack
Two systems reused the same RSA modulus n and only changed the public exponent. The ciphertexts c1 and c2 of the same…
CryptographyLevel 3★★★☆☆Cryptanalysis - Diffie-Hellman with a Small Prime
An old IoT device performed Diffie-Hellman key exchange with a prime p of only 36 bits. handshake.txt contains p, g, A…
LinuxLevel 4★★★★☆Linux-Kernel Module. Gaining Root via a Vulnerable Driver
This challenge analyzes a vulnerable character-device driver as a safe user-space simulation. No real kernel module is…
LinuxLevel 4★★★★☆Linux-Buffer Overflow. Exploiting a gets() Vulnerability
A vulnerable SUID C binary with protections disabled is provided. Exploit its buffer overflow to redirect control flow…
Network SecurityLevel 4★★★★☆Network Analysis - Rebuilding Chunked gzip HTTP from TCP
capture.pcap records two HTTP exchanges over one TCP connection. The server's segments are reordered and some are…
Network SecurityLevel 4★★★★☆Network Analysis - TCP Retransmission Covert Channel
capture.pcap contains TCP retransmissions with duplicate sequence numbers. Extract retransmissions whose payload…
CryptographyLevel 4★★★★☆Cryptanalysis - DSA Nonce Reuse Key Recovery
/challenge/signatures.json, created with fresh keys at every start, holds the DSA public parameters (p of 1024 bits, q…
CryptographyLevel 4★★★★☆Cryptanalysis - Wiener's Attack on RSA
An embedded-device team made the RSA private exponent d very small to speed up decryption. The public exponent e in…
CryptographyLevel 4★★★★☆Cryptanalysis - Recovering an LCG's Hidden Parameters
A service generated both session tokens and an encryption keystream from a linear congruential generator x_{k+1} =…
LinuxLevel 5★★★★★Linux-eBPF Rootkit. Unmasking a Hidden Process
This challenge safely recreates eBPF-rootkit investigation as offline evidence analysis. Without loading eBPF, tell…