Find the flag, flag finder.

• Flag Format: /flag{.+}/

Provided foren-steg.docx

Solution

The file provided to us appears to be a docx file. Let us see what happens when we try to open it.

There appears to be nothing in the file but gibberish...

Find the flag.

Solution

The source of the problem is as shown.

#!/usr/bin/env node
var parser = require('http-string-parser');

var net = require('net');

var server_tcp = net.createServer();

server_tcp.on('connection', function(socket) {
    

c = 7404228387482887479261869746749991746176804495927055118318206683570516448983801743960459361546161134428690426222368709863453442050071171756423599377401597984440754435058668926603178633761668515076496069751847161724033187368679875259918093224187811267691876198273870870578467510184510086298582204521702946045220312770122458237518246424165432296119053607094777200284200814236416350304918483690156578148133652864328594441673632360773823893061942585188618198600179924877899949396771723157015085683434661302154230334257765610040158570863416499816053904560634890245995407176180498179848769133967582005361790108725945277949845769358752674332269800138008126120486961174643630274131401283073800170609863393091462716402062974615038997250596862336175333249971111165958082179351116528188875511999901288868170989351009565637749016012554778609401305705599425503266370571838403199592830285591168821852287944019050110517938219347052153238370382065390639346971764343981632465382255796047103032366703706122266986406432114737513202337430860123189821063638894815952679576109060674029276361130756827095433943772560556432939992933276440340090287373085788774415087792787958810051460428461265815708830858361853853472340042568141996425244740239642623958541083311687869085046368156034023773742764525490982352637357523475031768768619981883253061696021829604666466769997506990572364386730754183019245389791086458671560767393577689687174730155049027616849606316072012661663516661756810877578172095321431600121667891545760511844723167476314345937930753837239733394626157660380103339672690094231220365695508657679602754981411231543816566131037225152153015287164171129157814773590352342570677841639550177097704155982858059402540582839885549452130954935219771327861980762934458786390322073771612324195542640000816993296528925039288704714097937261854536340516727095307316259517387188619927408613685678242056200319636422554100280245820480283675364454021450870487344889261

Find the flag.

Source is as follows

#!/usr/bin/env python3

import random
import time
import string
import signal

# use secure seed
random.seed(int(time.time()))

with open('flag.txt') as f:
	flag = f.read()

# large constant prime
p = 174807157365465092731323561678522236549173502913317875393564963123330281052524687450754910240009920154525635325209526987433833785499384204819179549544106498491589834195860008906875039418684191252537604123129659746721614402346449135195832955793815709136053198207712511838753919608894095907732099313139446299843

c = 26191355940216514058828050272090150139390105143316571288916153959981987155364392954681002096093811060534927092859120901667895980558351695183915403894182364524347204398303912481028969683750214274848084070775246727321046148252133500795342545499148992521849021332747338401076716206206836615083856166994789822570460117243518366900792518256064537225383342326351881682268623120346344160800766471622876341688831087817377673995827709465873793531598458486278334606573583545504597466349568081151696945328172365621531283265041924009357925158333224321566901753418442265655624943219944771093126875477706910554618181364928356402397

c = 49938873005546615435687311504872509785022284769848698526216639826561007249140360312632267256915204926681345807364733487154803200306964789424438457669341375204871001335059277860364152540205309441986059468568646721718475252818788849738581432943901958543446753508706429359356503196241596325655490713282416769960

c = 2911901299590689319468053634625275622654003904978205739380623481723661641396883678700531176998074009090944130064383792213854734101182591054606781359574544120823690362905523398270489939706547990345246231530733316646360394579721797156381054207414615333776383945252214100458075195770993971636731892198913293107313263096802400950280001995889600269261084002962194522369348371580184194201319826916320073496756736378234176527727677896098180012125139057850531341929674855173384488699967535868594673470466436155672157436157446615623094626238560694456848398206751930925254978950059694877328019092454478343535457958785859310484

Time for RSA!

e = 65537

n = 134023913680045880492110426626164090971954352532495944119602241841766743315344885078078359876157853261789964632342961459801834169156073972150056251259429043527344585589350222304649100454018523375146422111308080990153227407607374257909945989989405880451908900962388521742688809203045971595430040363546058882461

one fish twofish red fish blowfish

0xcaae8ee4f458ff776860e57141313e1e145423932e79e799d5133af8610e40d 94299046d28022d0b0efaa7fd3177b87e8e8530667111180e47da98f84846d753 cf9afa7c2635c93cf93ef8035b2217c05e192e3d2547e084c86085c2b83ef2b5

Solution

The...