Fri, 05 June 2020, 09:00 UTC — Sun, 07 June 2020, 09:00 UTC
On-line
A Defenit CTF event.
Format: Jeopardy
Official URL: https://ctf.defenit.kr/
This event's future weight is subject of public voting!
Event organizersThe First organized CTF, by Defenit
Categories are including Reversing, Pwnable, Web, Crypto, Forensics, Misc of varying levels of difficulty.
1st: 1,000,000 KRW
2nd: 300,000 KRW
3rd: 100,000 KRW
426 teams total
Place | Team | CTF points | Rating points | |
---|---|---|---|---|
1 | ToEatSushi | 17915.000 | 47.760 | |
2 | The_Duck | 17009.000 | 34.612 | |
3 | noar | 14894.000 | 27.813 | |
4 | zer0pts | 12098.000 | 22.096 | |
5 | 0ops | 8001.000 | 15.441 | |
6 | Balsn | 7891.000 | 14.498 | |
7 | TokyoWesterns | 7802.000 | 13.811 | |
8 | NationalIntelligence | 7526.000 | 13.017 | |
9 | jinmo123 | 7113.000 | 12.135 | |
10 | CTF.SG | 6308.000 | 10.796 | |
11 | avicii | 5941.000 | 10.090 | |
12 | NeSEBY | 5512.000 | 9.337 | |
13 | The Flat Network Society | 5317.000 | 8.924 | |
14 | Social Service Agent | 5206.000 | 8.645 | |
15 | bi0s | 5178.000 | 8.494 | |
16 | dotsu- | 5083.000 | 8.268 | |
17 | GoN | 4690.000 | 7.656 | |
18 | 2u1q | 4669.000 | 7.550 | |
19 | catsecurity | 3834.000 | 6.367 | |
20 | NICHTS? | 3465.000 | 5.813 | |
21 | Corrupted Pwnis | 3283.000 | 5.513 | |
22 | ADDVulcan | 3265.000 | 5.438 | |
23 | pwnsuky | 3001.000 | 5.038 | |
24 | MitAh | 2588.000 | 4.445 | |
25 | Dongmin Oneman Show | 2445.000 | 4.214 | |
26 | 0pentoall | 2230.000 | 3.891 | |
27 | N0Named | 2227.000 | 3.853 | |
28 | HATS Singapore | 2162.000 | 3.735 | |
29 | HTHT | 2068.000 | 3.580 | |
30 | swag | 2049.000 | 3.527 | |
31 | Regular Fellows | 1977.000 | 3.406 | |
32 | can | 1935.000 | 3.326 | |
33 | The Additional Payphones | 1801.000 | 3.124 | |
34 | null2root | 1787.000 | 3.084 | |
35 | d4rkc0de | 1743.000 | 3.006 | |
36 | RooterX | 1671.000 | 2.891 | |
37 | KUDoS | 1668.000 | 2.869 | |
38 | Skiddies | 1473.000 | 2.592 | |
39 | S33DMON | 1403.000 | 2.482 | |
40 | certis | 1395.000 | 2.456 | |
41 | ISITDTU | 1373.000 | 2.413 | |
42 | F03v3ryY0ung | 1343.000 | 2.359 | |
43 | Vox Dei | 1298.000 | 2.286 | |
44 | y011d4 | 1293.000 | 2.266 | |
45 | Infektion | 1289.000 | 2.249 | |
46 | zepto | 1285.000 | 2.232 | |
47 | vubar | 1235.000 | 2.154 | |
48 | HurriCan Laps | 1222.000 | 2.126 | |
49 | Pat and Mat | 1189.000 | 2.072 | |
50 | warlock_rootx | 1156.000 | 2.019 | |
51 | the3000 | 1145.000 | 1.994 | |
52 | tsu | 1097.000 | 1.921 | |
53 | S41n70V13n70 | 1092.000 | 1.906 | |
54 | OSUSEC | 1067.000 | 1.864 | |
55 | IPFactory | 1053.000 | 1.838 | |
56 | PFS | 1032.000 | 1.802 | |
57 | RevEng | 996.000 | 1.747 | |
58 | NBQ | 992.000 | 1.734 | |
59 | JJ | 992.000 | 1.727 | |
61 | bopsled | 967.000 | 1.680 | |
62 | PwnaSonic | 962.000 | 1.667 | |
63 | TSG | 955.000 | 1.652 | |
64 | Kuality | 944.000 | 1.631 | |
65 | D34DL1FT | 911.000 | 1.582 | |
66 | Contrail | 881.000 | 1.536 | |
67 | y0d31 | 881.000 | 1.531 | |
68 | ByteForc3 | 878.000 | 1.522 | |
69 | HCS | 865.000 | 1.499 | |
70 | Fword | 847.000 | 1.470 | |
71 | SCP | 844.000 | 1.461 | |
72 | KSJMT | 844.000 | 1.457 | |
73 | ook | 844.000 | 1.452 | |
74 | ./Vespiary | 844.000 | 1.448 | |
75 | AudiR8 | 808.000 | 1.395 | |
76 | InfosecIITG | 794.000 | 1.373 | |
77 | paulie | 777.000 | 1.346 | |
78 | ZH3R0 | 766.000 | 1.327 | |
79 | kknock | 763.000 | 1.319 | |
80 | InfoSecIITR | 746.000 | 1.293 | |
81 | ferb300 | 727.000 | 1.264 | |
82 | bratpid | 726.000 | 1.259 | |
83 | SecurityFactorial | 714.000 | 1.239 | |
84 | 0x5C71873F | 680.000 | 1.191 | |
85 | Senko | 677.000 | 1.183 | |
86 | n0paew | 677.000 | 1.180 | |
87 | noraneco | 666.000 | 1.162 | |
88 | TeamCC | 666.000 | 1.159 | |
89 | onotch | 663.000 | 1.152 | |
90 | VD | 649.000 | 1.130 | |
91 | Dashu | 646.000 | 1.124 | |
92 | dozty | 646.000 | 1.121 | |
93 | ThirtyNogada | 627.000 | 1.093 | |
94 | JFT | 626.000 | 1.088 | |
95 | ipwn 11 pro max | 614.000 | 1.070 | |
96 | Superrrrr | 596.000 | 1.043 | |
97 | Claremont Hackers | 579.000 | 1.018 | |
98 | testing1234 | 565.000 | 0.997 | |
99 | Shellphish | 549.000 | 0.973 | |
100 | LDKM0617 | 546.000 | 0.967 | |
101 | 0x8Layer | 546.000 | 0.964 | |
102 | progfay | 546.000 | 0.962 | |
103 | pollybyte | 526.000 | 0.933 | |
104 | Tux0 | 499.000 | 0.895 | |
105 | SWV_L | 499.000 | 0.893 | |
106 | IJCT | 499.000 | 0.890 | |
107 | SakanaCushion | 499.000 | 0.888 | |
108 | 0xBad | 496.000 | 0.882 | |
109 | whitehathacker | 496.000 | 0.880 | |
110 | Patchwork | 482.000 | 0.860 | |
111 | Invaders | 482.000 | 0.858 | |
112 | CodeCure | 479.000 | 0.852 | |
113 | QuasarB | 479.000 | 0.850 | |
114 | biark0v | 479.000 | 0.848 | |
115 | WatchNekos | 479.000 | 0.846 | |
116 | NUNNA NA DIE | 468.000 | 0.830 | |
117 | K0nFu53D C@ | 468.000 | 0.828 | |
118 | ZeroMemory | 468.000 | 0.826 | |
119 | panghuling | 465.000 | 0.820 | |
120 | b4dWH4k3r | 465.000 | 0.819 | |
121 | GreenColibry | 465.000 | 0.817 | |
122 | nopesled | 465.000 | 0.816 | |
123 | STeam | 465.000 | 0.814 | |
124 | HackademINT | 448.000 | 0.790 | |
125 | hfat | 448.000 | 0.788 | |
126 | Isaac | 448.000 | 0.787 | |
127 | RedKnights | 398.000 | 0.719 | |
128 | SJCTF | 398.000 | 0.717 | |
129 | HackingForSoju | 348.000 | 0.649 | |
130 | SSAT | 348.000 | 0.648 | |
131 | tiangeng | 316.000 | 0.604 | |
132 | Ficus | 316.000 | 0.602 | |
133 | BaaaaaaaaaaarkingDog | 301.000 | 0.581 | |
134 | zclfly | 301.000 | 0.579 | |
135 | CSI | 301.000 | 0.578 | |
136 | OAAOAOAO | 301.000 | 0.577 | |
137 | YagamiKou | 301.000 | 0.576 | |
138 | NorthWest | 301.000 | 0.574 | |
139 | sidhartha | 298.000 | 0.569 | |
140 | HTsP Junior | 298.000 | 0.568 | |
141 | Legion | 298.000 | 0.567 | |
142 | pmab | 298.000 | 0.565 | |
143 | Wani Hackase | 298.000 | 0.564 | |
144 | matiii | 298.000 | 0.563 | |
145 | FFF | 298.000 | 0.562 | |
146 | Pwnie Island | 298.000 | 0.561 | |
147 | NYXL | 298.000 | 0.560 | |
148 | Kerberos | 298.000 | 0.559 | |
149 | Shonan | 298.000 | 0.557 | |
150 | JHyeon | 298.000 | 0.556 | |
151 | 3358 | 281.000 | 0.533 | |
152 | vCryptis | 281.000 | 0.532 | |
153 | jammy | 281.000 | 0.531 | |
154 | M4dH4t | 281.000 | 0.530 | |
155 | NaNplusOne | 281.000 | 0.529 | |
156 | t3c | 281.000 | 0.528 | |
157 | Arnold | 281.000 | 0.527 | |
158 | Neptunians | 278.000 | 0.522 | |
159 | RyotaK | 278.000 | 0.521 | |
160 | sl33ke | 267.000 | 0.505 | |
161 | xatec50612 | 267.000 | 0.504 | |
162 | WebSpiders | 267.000 | 0.503 | |
163 | teamkrul | 267.000 | 0.502 | |
164 | xyper | 267.000 | 0.502 | |
165 | MrExplosive | 267.000 | 0.501 | |
166 | ISwearIGoogledIt | 267.000 | 0.500 | |
167 | 5minworkers | 267.000 | 0.499 | |
168 | matkapwn | 267.000 | 0.498 | |
169 | ddddhm | 267.000 | 0.497 | |
170 | anton3 | 248.000 | 0.471 | |
171 | Hungry | 248.000 | 0.470 | |
172 | kasiatutej | 201.000 | 0.407 | |
173 | Bat Squad | 201.000 | 0.406 | |
174 | testcheap | 201.000 | 0.405 | |
175 | Spirit | 201.000 | 0.404 | |
176 | Djavaa | 201.000 | 0.404 | |
177 | drogon | 201.000 | 0.403 | |
178 | soulctf | 201.000 | 0.402 | |
179 | GML | 201.000 | 0.401 | |
180 | 欸欸欸 | 201.000 | 0.401 | |
181 | tadaaa | 198.000 | 0.396 | |
182 | ZombieBot | 167.000 | 0.354 | |
183 | Chocolate Forest | 167.000 | 0.353 | |
184 | qbao | 167.000 | 0.352 | |
185 | Gladiator | 100.000 | 0.262 | |
186 | kitae | 100.000 | 0.262 | |
187 | KXTIMAKHUS | 100.000 | 0.261 | |
188 | KXTIUpDown | 100.000 | 0.260 | |
189 | weTryToHack | 100.000 | 0.260 | |
190 | oOo | 100.000 | 0.259 | |
191 | AlphaSec | 100.000 | 0.258 | |
192 | KUCS2020 | 100.000 | 0.258 | |
193 | p4ng | 100.000 | 0.257 | |
194 | Thomas | 100.000 | 0.256 | |
195 | BOGGLE IS | 100.000 | 0.256 | |
196 | KXTILittleBoys2 | 100.000 | 0.255 | |
197 | grep | 100.000 | 0.255 | |
198 | Boss | 100.000 | 0.254 | |
199 | tr1py9uy | 100.000 | 0.253 | |
200 | The Team | 100.000 | 0.253 | |
201 | PP Farmers | 100.000 | 0.252 | |
202 | LoIicore | 100.000 | 0.252 | |
203 | Intentions | 100.000 | 0.251 | |
204 | HoeSmackers | 100.000 | 0.250 | |
205 | brigante | 100.000 | 0.250 | |
206 | RH01 | 100.000 | 0.249 | |
207 | Enigma | 100.000 | 0.249 | |
208 | novus | 100.000 | 0.248 | |
209 | jsutset | 100.000 | 0.248 | |
210 | MTS7L | 100.000 | 0.247 | |
211 | Security First | 100.000 | 0.246 | |
212 | S1m0hYa | 100.000 | 0.246 | |
213 | Ains3tin | 100.000 | 0.245 | |
214 | ph03n1x | 100.000 | 0.245 | |
215 | score_gazer | 100.000 | 0.244 | |
216 | kxtiSnow | 100.000 | 0.244 | |
217 | MJ12 | 100.000 | 0.243 | |
218 | KXTI qwe | 100.000 | 0.243 | |
219 | p3tj0n95 | 100.000 | 0.242 | |
220 | UrlNo | 100.000 | 0.242 | |
221 | xrzhev | 100.000 | 0.241 | |
222 | 2yang | 100.000 | 0.241 | |
223 | New beginner | 100.000 | 0.240 | |
224 | ARO7I | 100.000 | 0.240 | |
225 | KimJunTaeDdaGgaRri | 100.000 | 0.239 | |
226 | AnarkoCyber | 100.000 | 0.239 | |
227 | h4ck7u5 | 100.000 | 0.238 | |
228 | CL4Y | 100.000 | 0.238 | |
229 | kkingkkang | 100.000 | 0.238 | |
230 | light reflect me | 100.000 | 0.237 | |
231 | info info | 100.000 | 0.237 | |
232 | entr0py | 100.000 | 0.236 | |
233 | 4RGOS | 100.000 | 0.236 | |
234 | Enesdex | 100.000 | 0.235 | |
235 | Unstoppable | 100.000 | 0.235 | |
236 | pench | 100.000 | 0.234 | |
237 | Ally Squad | 100.000 | 0.234 | |
238 | StarLabs | 100.000 | 0.234 | |
239 | crayontheft | 100.000 | 0.233 | |
240 | Soviet Yun Yun | 100.000 | 0.233 | |
241 | DarkCrawlers | 100.000 | 0.232 | |
242 | teamForFun | 100.000 | 0.232 | |
243 | cdc | 100.000 | 0.232 | |
244 | 14degree | 100.000 | 0.231 | |
245 | m0nst3r | 100.000 | 0.231 | |
246 | KXTIqwr | 100.000 | 0.230 | |
247 | TeamAlpha | 100.000 | 0.230 | |
248 | erikkabir | 100.000 | 0.230 | |
249 | wongsinteng | 100.000 | 0.229 | |
250 | poorya7899 | 100.000 | 0.229 | |
251 | Yuby76 | 100.000 | 0.228 | |
252 | OverDover | 100.000 | 0.228 | |
253 | noob99 | 100.000 | 0.228 | |
254 | echobash | 100.000 | 0.227 | |
255 | CommandMaster | 100.000 | 0.227 | |
256 | teamst0rm | 100.000 | 0.227 | |
257 | j0k3r | 100.000 | 0.226 | |
258 | KompetenzZentrum | 100.000 | 0.226 | |
259 | Mesz0rs | 100.000 | 0.225 | |
260 | DROP TABLE flags | 100.000 | 0.225 | |
261 | D3KUOFFICIAL | 100.000 | 0.225 | |
262 | dimihacker | 100.000 | 0.224 | |
263 | 4katsuk1 | 100.000 | 0.224 | |
264 | hanahouse | 100.000 | 0.224 | |
265 | Yeol | 100.000 | 0.223 | |
266 | PStar | 100.000 | 0.223 | |
267 | Stuca | 100.000 | 0.223 | |
268 | periapsis | 100.000 | 0.222 | |
269 | FuzzyDucks | 100.000 | 0.222 | |
270 | 5drone | 100.000 | 0.222 | |
271 | keiser | 100.000 | 0.221 | |
272 | kanyewest | 100.000 | 0.221 | |
273 | Team0xDeadbeef | 100.000 | 0.221 | |
274 | After_the_CM | 100.000 | 0.220 | |
275 | BLANK | 100.000 | 0.220 | |
276 | RedZone | 100.000 | 0.220 | |
277 | ZenSec | 100.000 | 0.220 | |
278 | P01TERGEIST | 100.000 | 0.219 | |
279 | 00000000 | 100.000 | 0.219 | |
280 | UwU | 100.000 | 0.219 | |
281 | Ondris | 100.000 | 0.218 | |
282 | Dark Motel | 100.000 | 0.218 | |
283 | 3 S U M | 100.000 | 0.218 | |
284 | HackWara | 100.000 | 0.217 | |
285 | p2n | 100.000 | 0.217 | |
286 | lifeise99 | 100.000 | 0.217 | |
287 | fr334aks | 100.000 | 0.217 | |
288 | IGRUS | 100.000 | 0.216 | |
289 | ReaperOfWorlds | 100.000 | 0.216 | |
290 | CxData x Retru | 100.000 | 0.216 | |
291 | fLAGers | 100.000 | 0.215 | |
292 | hvsblogger | 100.000 | 0.215 | |
293 | woolf | 100.000 | 0.215 | |
294 | PowerSecurity | 100.000 | 0.215 | |
295 | imagin | 100.000 | 0.214 | |
296 | IKTeam | 100.000 | 0.214 | |
297 | whereTheFuckIM | 100.000 | 0.214 | |
298 | navigator | 100.000 | 0.213 | |
299 | Spikers | 100.000 | 0.213 | |
300 | mark0 | 100.000 | 0.213 | |
301 | Insight Harbor | 100.000 | 0.213 | |
302 | Purple Penguins | 100.000 | 0.212 | |
303 | Stugrandca | 100.000 | 0.212 | |
304 | Kian Team | 100.000 | 0.212 | |
305 | Team Fr34ks | 100.000 | 0.212 | |
306 | ahengers | 100.000 | 0.211 | |
307 | Iceclue | 100.000 | 0.211 | |
308 | burner herz0g | 100.000 | 0.211 | |
309 | eshe | 100.000 | 0.211 | |
310 | sty | 100.000 | 0.210 | |
311 | TixwaIsParfait2 | 100.000 | 0.210 | |
312 | spoilers | 100.000 | 0.210 | |
313 | AnonyBit | 100.000 | 0.210 | |
314 | TeamProbably | 100.000 | 0.209 | |
315 | abenben | 100.000 | 0.209 | |
316 | nuk3 | 100.000 | 0.209 | |
317 | Pr0f3ss0r | 100.000 | 0.209 | |
318 | w0mbat | 100.000 | 0.208 | |
319 | 4everN000bs | 100.000 | 0.208 | |
320 | c10r0x | 100.000 | 0.208 | |
321 | HhhM | 100.000 | 0.208 | |
322 | F0rc3IsStr0ng | 100.000 | 0.207 | |
323 | R3SJster | 100.000 | 0.207 | |
324 | Canary | 100.000 | 0.207 | |
325 | Call Z One | 100.000 | 0.207 | |
326 | y2580 | 100.000 | 0.207 | |
327 | gjfzm123 | 100.000 | 0.206 | |
328 | SIS | 100.000 | 0.206 | |
329 | jongsangkuun | 100.000 | 0.206 | |
330 | SeventhOA | 100.000 | 0.206 | |
331 | Z3Ro | 100.000 | 0.205 | |
332 | Kernel Sanders | 100.000 | 0.205 | |
333 | zeolpoi | 100.000 | 0.205 | |
334 | Xia Tianguo | 100.000 | 0.205 | |
335 | Code Black | 100.000 | 0.205 | |
336 | gruf | 100.000 | 0.204 | |
337 | ChaigncHackademyy | 100.000 | 0.204 | |
338 | bob8gook | 100.000 | 0.204 | |
339 | deb0sca | 100.000 | 0.204 | |
340 | shit1234 | 100.000 | 0.204 | |
341 | deNableD | 100.000 | 0.203 | |
342 | outOfCheese | 100.000 | 0.203 | |
343 | Maaa | 100.000 | 0.203 | |
344 | L33t Dev | 100.000 | 0.203 | |
345 | DayMon | 100.000 | 0.203 | |
346 | ty007 | 100.000 | 0.202 | |
347 | senic | 100.000 | 0.202 | |
348 | JT523 | 100.000 | 0.202 | |
349 | SUV | 100.000 | 0.202 | |
350 | Lazzaro | 100.000 | 0.202 | |
351 | N33rdZ | 100.000 | 0.201 | |
352 | nubza | 100.000 | 0.201 | |
353 | Tzilacatzin | 100.000 | 0.201 | |
354 | Selflessgg | 100.000 | 0.201 | |
355 | mikejam | 100.000 | 0.201 | |
356 | GameBak | 100.000 | 0.200 | |
357 | thrumbos | 100.000 | 0.200 | |
358 | MatPaczy | 100.000 | 0.200 | |
359 | QWarty | 100.000 | 0.200 | |
360 | Don | 100.000 | 0.200 | |
361 | Dazai | 100.000 | 0.199 | |
362 | kaleta | 100.000 | 0.199 | |
363 | manmanboza | 100.000 | 0.199 | |
364 | Educmd | 100.000 | 0.199 | |
365 | 0neP01nt | 100.000 | 0.199 | |
366 | On1onCTF | 100.000 | 0.199 | |
367 | Team Felix | 100.000 | 0.198 | |
368 | salespies | 100.000 | 0.198 | |
369 | c4p74In1r5 | 100.000 | 0.198 | |
370 | K22TMT | 100.000 | 0.198 | |
371 | y3ti0ps | 100.000 | 0.198 | |
372 | g0tiu5a | 100.000 | 0.197 | |
373 | newbie0 | 100.000 | 0.197 | |
374 | djdjdjdj | 100.000 | 0.197 | |
375 | KingJL | 100.000 | 0.197 | |
376 | ash3r | 100.000 | 0.197 | |
377 | SyaganZang | 100.000 | 0.197 | |
378 | R3H4CK | 100.000 | 0.196 | |
379 | toolate | 100.000 | 0.196 | |
380 | Team M | 100.000 | 0.196 | |
381 | fxploit | 100.000 | 0.196 | |
382 | disso1p1 | 100.000 | 0.196 | |
383 | Digital Dragons | 100.000 | 0.196 | |
384 | dcua | 100.000 | 0.195 | |
385 | roseofsharon | 100.000 | 0.195 | |
386 | Albert5888 | 100.000 | 0.195 | |
387 | XYZdefault | 100.000 | 0.195 | |
388 | YungScoob | 100.000 | 0.195 | |
389 | kilgrave | 100.000 | 0.195 | |
390 | TheUnpwnable | 100.000 | 0.195 | |
391 | subinsoohyun | 100.000 | 0.194 | |
392 | PeterPan | 100.000 | 0.194 | |
393 | stankc | 100.000 | 0.194 | |
394 | wckd.cr3w | 100.000 | 0.194 | |
395 | Maple | 100.000 | 0.194 | |
396 | B216 | 100.000 | 0.194 | |
397 | n3wb13 | 100.000 | 0.193 | |
398 | Banbanji | 100.000 | 0.193 | |
399 | k1r170 | 100.000 | 0.193 | |
400 | wcg6m | 100.000 | 0.193 | |
401 | Just Me | 100.000 | 0.193 | |
402 | adonis | 100.000 | 0.193 | |
403 | manishkumarr | 100.000 | 0.193 | |
404 | D0bu | 100.000 | 0.192 | |
405 | wzy | 100.000 | 0.192 | |
406 | Lab104 | 100.000 | 0.192 | |
407 | testbot | 100.000 | 0.192 | |
408 | arrester | 100.000 | 0.192 | |
409 | jeolla | 100.000 | 0.192 | |
410 | page2me | 100.000 | 0.192 | |
411 | Loopback | 100.000 | 0.191 | |
412 | Lucifer07 | 100.000 | 0.191 | |
413 | break_the_code | 100.000 | 0.191 | |
414 | Lions | 100.000 | 0.191 | |
415 | acdwas | 100.000 | 0.191 | |
416 | Pwn October | 100.000 | 0.191 | |
417 | 0x4254 | 100.000 | 0.191 | |
418 | AdiPratama15 | 100.000 | 0.190 | |
419 | HunterX | 100.000 | 0.190 | |
420 | 182 16 178 170 8886 | 100.000 | 0.190 | |
421 | r5 | 100.000 | 0.190 | |
422 | namy007 | 100.000 | 0.190 | |
423 | sandatindo | 100.000 | 0.190 | |
424 | hanto | 100.000 | 0.190 | |
425 | Blackhood | 100.000 | 0.189 | |
426 | NickGur | 100.000 | 0.095 | |
427 | n0 | 100.000 | 0.095 |
why can't open https://ctf.defenit.kr/
how to register to join the ctf