THM Holiday Hack 2026
Writeups

Author: Hubert Feyrer / hubertf, 2026-08-04


TryHackMe Holiday Hack 2026 - The Byte Lotus Hotel

Summary

TryHackMe's Holiday Hack Challenge played 14 challenges from many categories, each one on a new day. As an experiment, AI was used at length as a tool for analysis of the situation and downloads as well as in creating solutions and summarizing them in writeups. This automated first step was always followed by thorough manual review of all parts, and adding manual changes where needed.

Writeups

DayCategoryChallengeDifficultyWhat it is
01 AI The Concierge Knows Too Much Very Easy Prompt injection / broken auth: VERA "verifies" a guest by name only, so claiming a VIP name makes her repeat her system prompt and leak the secret.
02 Web Room 404 Very Easy An exposed .git directory; git-dumper reassembles the repo and a staging flag was committed to the README.
03 Cloud Complimentary Easy A public unauthenticated Cognito Identity Pool mints temporary AWS creds; the guest role can dynamodb scan the profile table straight to the flag.
04 Forensics Packed Light Easy A pcap of a keylogger exfiltrating keystrokes one Base64 byte per cookie; XOR each with 0x48 to rebuild the typed flag.
05 boot2root Beach Bar Easy A leaked demo login unlocks a playlist import that deserializes YAML unsafely (RCE), then a reused staff password via su gives root.
06 OSINT Overheard at Breakfast Easy An email address plus a Gravatar profile (keyed by md5(email)) that hands over a Base64 prize - the flag.
07 boot2root Do Not Disturb Medium NoSQL login bypass and EJS template injection for a shell, then a Node --inspect debugger pivot and the disk group to read root.
08 Web Towel on the Sunbed Medium A TOCTOU race on the once-per-day reward claim, fired concurrently to reach Whale Vault status and the flag.
09 Cloud CryptoCabana Medium A leaked Azure Storage SAS token leads to a service principal, then to Key Vault - where the flag hides in a secret's pre-rotation version.
10 Web The Hollow Shell Medium A Zip Slip path-traversal in the shell-upload extractor overwrites the login template, turning arbitrary write into Jinja2 SSTI and remote code execution.
11 boot2root Infinity Pool Medium OS command injection in a resort booking site gives a user shell; leaked FreePBX UCP creds and a voicemail Caller ID surface the root automation token, and a second command injection in the root-run job runner reads the root flag.
12 Forensics After Hours Medium WMI event subscription persistence carved out of a raw CIM repository: a custom Win32_HardwareTelemetry class hides a deflated .NET assembly that adds a backdoor account whose password is the flag.
13 AI The Guestbook Medium Indirect prompt injection: a guestbook entry forges "manager" approval by text, the next entry's override: directive runs a shell command, and a Base64 instruction slips the flag past VERA's output redaction.
14 Forensics Management Wants a Word Hard A KAPE triage: a Chrome saved password recovered offline via DPAPI (after cracking the SAM) unlocks a VeraCrypt volume, decrypted in Python, whose "invoice" PDF image holds the flag.

Visual summary

Visual summary of the 14 Holiday Hack challenges

Visual summary of the event - illustrated with Google Gemini.