traffic-e

Catégorie: Crypto Difficulté: medium Flag: CTF{46b1d043b3d2d98a267455affce276c47a1f2bfb940881d1e9725c798373f532}

Challenge

3KB

traffic-e.zip

archive

Ouvrir

Description

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Good luck.

Flag format: CTF{random-hex}

Analyse du pcap

On trouve 26 frames dans le fichier et on peut trouver la clé public RSA dans la n°6

Avec un outil comme RsaCtfTool on peut casser la clé privée

$ ./RsaCtfTool.py --private -n 1300556443385702960287370880066951363059458853608419778980399106681258797515744867649068169234104827392051556571142405277681682030539978956790151962476764197038895389999034906026782855543935783433997596921912146618367339288840191094863590166756750397571840198677668908227545077721957613740525469652282292908679 -e 106645361573597107845396067866499068630105849159408665310862014583870062061704662230754284832387896920427209753236862548800746662398609212688373613186979102970308417884832531601035544107102590028211579550508699494971288803583755640940424098301425895738898909222425910339731329121362635050810847489912118168559

[*] Performing wiener attack on /tmp/tmp32x_7kxt.
 22%|████████████████████████▋                                                                                         | 126/582 [00:00<00:00, 842874.49it/s]
[*] Attack success with wiener method !
[+] Total time elapsed min,max,avg: 0.0001/6.4226/0.9929 sec.

Results for /tmp/tmp32x_7kxt:

Private key :
-----BEGIN RSA PRIVATE KEY-----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==
-----END RSA PRIVATE KEY-----

Ensuite on enregistre la clé dans un fichier key.pem puis on l’ajoute dans Wireshark pour déchiffrer les données

Maintenant on peut lire les données échangées et dans la frame n°18 il y a le flag