The Captain's Comms

The Captain’s Comms

Difficulty: 🎄🎄🎄🎄🎄
Speak with Chimney Scissorsticks on Steampunk Island about the interesting things the captain is hearing on his new Software Defined Radio. You’ll need to assume the GeeseIslandsSuperChiefCommunicationsOfficer role.

Hints

Comms JWT Intro

From: Chimney Scissorsticks
A great introduction to JSON Web Tokens is available from Auth0.

Comms Abbreviations

From: Chimney Scissorsticks
I hear the Captain likes to abbreviate words in his filenames; shortening some words to just 1,2,3, or 4 letters.

Comms Journal

From: Chimney Scissorsticks
I’ve seen the Captain with his Journal visiting Pixel Island!

Comms Private Key

From: Chimney Scissorsticks
Find a private key, update an existing JWT!

Comms Web Interception Proxies

From: Chimney Scissorsticks
Web Interception proxies like Burp and Zap make web sites fun!

Solution

First steps

First thing first, I clicked everywhere and downloaded all the images I could access: Background, Just Watch This Owner’s Manual Volume I, Just Watch This Owner’s Manual Volume II, Just Watch This Appendix A - Decoder Index, Just Watch This: Owner’s Card, Captain’s To-Do List and Captain’s ChatNPT Initial To-Do List.

Then looking at the cookies I saw justWatchThisRole=eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJISEMgMjAyMyBDYXB0YWluJ3MgQ29tbXMiLCJpYXQiOjE2OTk0ODU3OTUuMzQwMzMyNywiZXhwIjoxODA5OTM3Mzk1LjM0MDMzMjcsImF1ZCI6IkhvbGlkYXkgSGFjayAyMDIzIiwicm9sZSI6InJhZGlvVXNlciJ9.BGxJLMZw-FHI9NRl1xt_f25EEnFcAYYu173iqf-6dgoa_X3V7SAe8scBbARyusKq2kEbL2VJ3T6e7rAVxy5Eflr2XFMM5M-Wk6Hqq1lPvkYPfL5aaJaOar3YFZNhe_0xXQ__k__oSKN1yjxZJ1WvbGuJ0noHMm_qhSXomv4_9fuqBUg1t1PmYlRFN3fNIXh3K6JEi5CvNmDWwYUqhStwQ29SM5zaeLHJzmQ1Ey0T1GG-CsQo9XnjIgXtf9x6dAC00LYXe1AMly4xJM9DfcZY_KjfP-viyI7WYL0IJ_UOtIMMN0u-XO8Q_F3VO0NyRIhZPfmALOM2Liyqn6qYMN0u-XO8Q_F3VO0NyRIhZPfmALOM2Liyqn6qYTjLnkg that is a signed JWT with an unknown key and decodes to:

HEADER  --> {"alg": "RS256", "typ": "JWT"}
PAYLOAD --> {"iss": "HHC 2023 Captain's Comms", "iat": 1699485795.3403327, "exp": 1809937395.3403327, "aud": "Holiday Hack 2023", "role": "radioUser"}

The rMonitor.tok and capsPubKey.key

The Captain doesn’t appear to be too tech savvy so I expected to find the file rMonitor.tok in its default directory. After a lot more than what I’d like to admit, I noticed that the /checkRole request was authenticating using the JWT as a Bearer token, and I was finally able to obtain rMonitor.tok and the capsPubKey.key:

thedead@dellian:~/hhc2023/The Captain's Comms$ curl -H 'Authorization: Bearer eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJISEMgMjAyMyBDYXB0YWluJ3MgQ29tbXMiLCJpYXQiOjE2OTk0ODU3OTUuMzQwMzMyNywiZXhwIjoxODA5OTM3Mzk1LjM0MDMzMjcsImF1ZCI6IkhvbGlkYXkgSGFjayAyMDIzIiwicm9sZSI6InJhZGlvVXNlciJ9.BGxJLMZw-FHI9NRl1xt_f25EEnFcAYYu173iqf-6dgoa_X3V7SAe8scBbARyusKq2kEbL2VJ3T6e7rAVxy5Eflr2XFMM5M-Wk6Hqq1lPvkYPfL5aaJaOar3YFZNhe_0xXQ__k__oSKN1yjxZJ1WvbGuJ0noHMm_qhSXomv4_9fuqBUg1t1PmYlRFN3fNIXh3K6JEi5CvNmDWwYUqhStwQ29SM5zaeLHJzmQ1Ey0T1GG-CsQo9XnjIgXtf9x6dAC00LYXe1AMly4xJM9DfcZY_KjfP-viyI7WYL0IJ_UOtIMMN0u-XO8Q_F3VO0NyRIhZPfmALOM2Liyqn6qYTjLnkg' https://captainscomms.com/jwtDefault/rMonitor.tok
eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJISEMgMjAyMyBDYXB0YWluJ3MgQ29tbXMiLCJpYXQiOjE2OTk0ODU3OTUuMzQwMzMyNywiZXhwIjoxODA5OTM3Mzk1LjM0MDMzMjcsImF1ZCI6IkhvbGlkYXkgSGFjayAyMDIzIiwicm9sZSI6InJhZGlvTW9uaXRvciJ9.f_z24CMLim2JDKf8KP_PsJmMg3l_V9OzEwK1E_IBE9rrIGRVBZjqGpvTqAQQSesJD82LhK2h8dCcvUcF7awiAPpgZpcfM5jdkXR7DAKzaHAV0OwTRS6x_Uuo6tqGMu4XZVjGzTvba-eMGTHXyfekvtZr8uLLhvNxoarCrDLiwZ_cKLViRojGuRIhGAQCpumw6NTyLuUYovy_iymNfe7pqsXQNL_iyoUwWxfWcfwch7eGmf2mBrdEiTB6LZJ1ar0FONfrLGX19TV25Qy8auNWQIn6jczWM9WcZbuOIfOvlvKhyVWbPdAK3zB7OOm-DbWm1aFNYKr6JIRDLobPfiqhKg

thedead@dellian:~/hhc2023/The Captain's Comms$ curl -H 'Authorization: Bearer eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJISEMgMjAyMyBDYXB0YWluJ3MgQ29tbXMiLCJpYXQiOjE2OTk0ODU3OTUuMzQwMzMyNywiZXhwIjoxODA5OTM3Mzk1LjM0MDMzMjcsImF1ZCI6IkhvbGlkYXkgSGFjayAyMDIzIiwicm9sZSI6InJhZGlvVXNlciJ9.BGxJLMZw-FHI9NRl1xt_f25EEnFcAYYu173iqf-6dgoa_X3V7SAe8scBbARyusKq2kEbL2VJ3T6e7rAVxy5Eflr2XFMM5M-Wk6Hqq1lPvkYPfL5aaJaOar3YFZNhe_0xXQ__k__oSKN1yjxZJ1WvbGuJ0noHMm_qhSXomv4_9fuqBUg1t1PmYlRFN3fNIXh3K6JEi5CvNmDWwYUqhStwQ29SM5zaeLHJzmQ1Ey0T1GG-CsQo9XnjIgXtf9x6dAC00LYXe1AMly4xJM9DfcZY_KjfP-viyI7WYL0IJ_UOtIMMN0u-XO8Q_F3VO0NyRIhZPfmALOM2Liyqn6qYTjLnkg' https://captainscomms.com/jwtDefault/keys/capsPubKey.key
-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAsJZuLJVB4EftUOQN1Auw
VzJyr1Ma4xFo6EsEzrkprnQcdgwz2iMM76IEiH8FlgKZG1U0RU4N3suI24NJsb5w
J327IYXAuOLBLzIN65nQhJ9wBPR7Wd4Eoo2wJP2m2HKwkW5Yadj6T2YgwZLmod3q
n6JlhN03DOk1biNuLDyWao+MPmg2RcxDR2PRnfBartzw0HPB1yC2Sp33eDGkpIXa
cx/lGVHFVxE1ptXP+asOAzK1wEezyDjyUxZcMMmV0VibzeXbxsXYvV3knScr2WYO
qZ5ssa4Rah9sWnm0CKG638/lVD9kwbvcO2lMlUeTp7vwOTXEGyadpB0WsuIKuPH6
uQIDAQAB
-----END PUBLIC KEY-----

Setting the value of the cookie justWatchThisRole to the content of rMonitor.tok I was able to access the Just Watch This Signal Display that returned a gif with clickable peaks highlighted in the image below:

Unfortunately, when clicking the peaks, I was being presented with an error requiring me to have the radioDecoder role.

The rDecoder.tok - Leap of faith

After so many failed attempts that it was just “not worth not to try” and in a total leap of faith, I eventually tried the url (https://captainscomms.com/jwtDefault/rDecoder.tok) and obtained the rDecoder.tok:

thedead@dellian:~/hhc2023/The Captain's Comms$ curl -H 'Authorization: Bearer eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJISEMgMjAyMyBDYXB0YWluJ3MgQ29tbXMiLCJpYXQiOjE2OTk0ODU3OTUuMzQwMzMyNywiZXhwIjoxODA5OTM3Mzk1LjM0MDMzMjcsImF1ZCI6IkhvbGlkYXkgSGFjayAyMDIzIiwicm9sZSI6InJhZGlvTW9uaXRvciJ9.f_z24CMLim2JDKf8KP_PsJmMg3l_V9OzEwK1E_IBE9rrIGRVBZjqGpvTqAQQSesJD82LhK2h8dCcvUcF7awiAPpgZpcfM5jdkXR7DAKzaHAV0OwTRS6x_Uuo6tqGMu4XZVjGzTvba-eMGTHXyfekvtZr8uLLhvNxoarCrDLiwZ_cKLViRojGuRIhGAQCpumw6NTyLuUYovy_iymNfe7pqsXQNL_iyoUwWxfWcfwch7eGmf2mBrdEiTB6LZJ1ar0FONfrLGX19TV25Qy8auNWQIn6jczWM9WcZbuOIfOvlvKhyVWbPdAK3zB7OOm-DbWm1aFNYKr6JIRDLobPfiqhKg' https://captainscomms.com/jwtDefault/rDecoder.tok
eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJISEMgMjAyMyBDYXB0YWluJ3MgQ29tbXMiLCJpYXQiOjE2OTk0ODU3OTUuMzQwMzMyNywiZXhwIjoxODA5OTM3Mzk1LjM0MDMzMjcsImF1ZCI6IkhvbGlkYXkgSGFjayAyMDIzIiwicm9sZSI6InJhZGlvRGVjb2RlciJ9.cnNu6EjIDBrq8PbMlQNF7GzTqtOOLO0Q2zAKBRuza9bHMZGFx0pOmeCy2Ltv7NUPv1yT9NZ-WapQ1-GNcw011Ssbxz0yQO3Mh2Tt3rS65dmb5cmYIZc0pol-imtclWh5s1OTGUtqSjbeeZ2QAMUFx3Ad93gR20pKpjmoeG_Iec4JHLTJVEksogowOouGyDxNAagIICSpe61F3MY1qTibOLSbq3UVfiIJS4XvGJwqbYfLdbhc-FvHWBUbHhAzIgTIyx6kfONOH9JBo2RRQKvN-0K37aJRTqbq99mS4P9PEVs0-YIIufUxJGIW0TdMNuVO3or6bIeVH6CjexIl14w6fg

This then allowed to access the content of the peaks in the previous image, revealing the content of the peaks:

Just Watch This CW Decoder
Just Watch This Audio-Text Decoder
Just Watch This RadioFax Decoder

TH3CAPSPR1V4T3F0LD3R - And signing petitions

The transmission machine required additional privileges, so I went after the captain’s private key. After ignoring the UPPER CASE for too long, I found it at the URL (https://captainscomms.com/jwtDefault/keys/TH3CAPSPR1V4T3F0LD3R/capsPrivKey.key) :

thedead@dellian:~/hhc2023/The Captain's Comms$ curl -H 'Authorization: Bearer eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJISEMgMjAyMyBDYXB0YWluJ3MgQ29tbXMiLCJpYXQiOjE2OTk0ODU3OTUuMzQwMzMyNywiZXhwIjoxODA5OTM3Mzk1LjM0MDMzMjcsImF1ZCI6IkhvbGlkYXkgSGFjayAyMDIzIiwicm9sZSI6InJhZGlvRGVjb2RlciJ9.cnNu6EjIDBrq8PbMlQNF7GzTqtOOLO0Q2zAKBRuza9bHMZGFx0pOmeCy2Ltv7NUPv1yT9NZ-WapQ1-GNcw011Ssbxz0yQO3Mh2Tt3rS65dmb5cmYIZc0pol-imtclWh5s1OTGUtqSjbeeZ2QAMUFx3Ad93gR20pKpjmoeG_Iec4JHLTJVEksogowOouGyDxNAagIICSpe61F3MY1qTibOLSbq3UVfiIJS4XvGJwqbYfLdbhc-FvHWBUbHhAzIgTIyx6kfONOH9JBo2RRQKvN-0K37aJRTqbq99mS4P9PEVs0-YIIufUxJGIW0TdMNuVO3or6bIeVH6CjexIl14w6fg' https://captainscomms.com/jwtDefault/keys/TH3CAPSPR1V4T3F0LD3R/capsPrivKey.key
-----BEGIN PRIVATE KEY-----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-----END PRIVATE KEY-----

Just so you know, as soon as this happened, I signed the petition Remove the Caps Lock key from the keyboard.

Having the private key, I used jwt.io to alter the JWT token to eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJISEMgMjAyMyBDYXB0YWluJ3MgQ29tbXMiLCJpYXQiOjE2OTk0ODU3OTUuMzQwMzMyNywiZXhwIjoxODA5OTM3Mzk1LjM0MDMzMjcsImF1ZCI6IkhvbGlkYXkgSGFjayAyMDIzIiwicm9sZSI6IkdlZXNlSXNsYW5kc1N1cGVyQ2hpZWZDb21tdW5pY2F0aW9uc09mZmljZXIifQ.N-8MdT6yPFge7zERpm4VdLdVLMyYcY_Wza1TADoGKK5_85Y5ua59z2Ke0TTyQPa14Z7_Su5CpHZMoxThIEHUWqMzZ8MceUmNGzzIsML7iFQElSsLmBMytHcm9-qzL0Bqb5MeqoHZYTxN0vYG7WaGihYDTB7OxkoO_r4uPSQC8swFJjfazecCqIvl4T5i08p5Ur180GxgEaB-o4fpg_OgReD91ThJXPt7wZd9xMoQjSuPqTPiYrP5o-aaQMcNhSkMix_RX1UGrU-2sBlL01FxI7SjxPYu4eQbACvuK6G2wyuvaQIclGB2Qh3P7rAOTpksZSex9RjtKOiLMCafTyfFng, assigning myself the GeeseIslandsSuperChiefCommunicationsOfficer role:

HEADER  --> {"alg": "RS256", "typ": "JWT"}
PAYLOAD --> {"iss": "HHC 2023 Captain's Comms", "iat": 1699485795.3403327, "exp": 1809937395.3403327, "aud": "Holiday Hack 2023", "role": "GeeseIslandsSuperChiefCommunicationsOfficer"}

The captainsTX - and discovering attention and reading weaknesses

With the new role, I was able to access the TX machine. The frequency 10426 Hz was fairly obvious from the RadioFax Decoder message, and I understood that 1224 and 1600 in the Audio-Text Decoder message were the Go-Date and Go-Time. Poking around with these values was not successful until I was got the hint on re-reading the Background, and understood that: a) reading is not my thing and b) I had to shift back 4 hours the Go-Time. That saved the day:

Thanks to @i81b4u

Thank you for making me try the CAPS!

Thanks to @dp

I would have probably never re-read the Background if it wasn’t for your hint!