0xVRIG/legacy-index.html at main · VRIG-RITSEC/0xVRIG · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Memory Corruption Lab</title>
<style>
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #0c0c0c;
  --panel-bg: #141414;
  --panel-border: #333;
  --text: #ddd;
  --text-dim: #999;
  --green: #4ec9b0;
  --blue: #569cd6;
  --amber: #ce9178;
  --red: #f44747;
  --yellow: #dcdcaa;
  --purple: #c586c0;
  --comment: #7fbf68;
  --font: 'Cascadia Code', 'Fira Code', 'JetBrains Mono', 'Consolas', monospace;
}

html, body { height: 100%; background: var(--bg); color: var(--text); font-family: var(--font); font-size: 13px; }

#app {
  display: flex; flex-direction: column; height: 100vh; overflow: hidden;
}

header {
  display: flex; align-items: center; gap: 1rem; padding: 0.5rem 1rem;
  border-bottom: 1px solid var(--panel-border); background: var(--panel-bg);
  flex-shrink: 0;
}
header h1 { font-size: 14px; color: var(--green); font-weight: normal; white-space: nowrap; }
nav { display: flex; gap: 0.15rem; flex-wrap: wrap; align-items: center; }
.nav-unit-label {
  font-size: 10px; color: var(--text-dim); text-transform: uppercase;
  letter-spacing: 0.05em; padding: 0.25rem 0.5rem; margin-left: 0.5rem;
  border-left: 1px solid var(--panel-border);
}
.nav-unit-label:first-child { margin-left: 0; border-left: none; }
nav button {
  background: transparent; border: 1px solid var(--panel-border); color: var(--text-dim);
  padding: 0.25rem 0.5rem; font-family: var(--font); font-size: 11px; cursor: pointer;
  transition: all 0.15s; min-width: 2em; text-align: center;
}
nav button:hover:not(:disabled) { border-color: var(--text-dim); color: var(--text); }
nav button.active { border-color: var(--green); color: var(--green); }
nav button.completed { border-color: var(--comment); color: var(--comment); }
nav button.completed::after { content: ' ✓'; font-size: 9px; }
nav button:disabled { opacity: 0.3; cursor: not-allowed; }

#badges { display: flex; gap: 0.5rem; margin-left: auto; }
.badge {
  font-size: 11px; padding: 0.15rem 0.5rem; border: 1px solid var(--yellow);
  color: var(--yellow); border-radius: 2px; white-space: nowrap;
}

main {
  flex: 1; display: grid; overflow: hidden;
  grid-template-columns: 1fr 1fr;
  grid-template-rows: 1fr 1fr;
  gap: 1px; background: var(--panel-border);
}

.panel {
  background: var(--panel-bg); display: flex; flex-direction: column; overflow: hidden;
}
.panel-hdr {
  padding: 0.35rem 0.75rem; font-size: 11px; color: var(--text-dim);
  border-bottom: 1px solid var(--panel-border); flex-shrink: 0;
  text-transform: uppercase; letter-spacing: 0.05em;
}
.panel-body { flex: 1; overflow-y: auto; padding: 0.75rem; }

/* Source panel */
#source-panel { grid-column: 1; grid-row: 1; }
#source-code {
  white-space: pre; line-height: 1.6; tab-size: 4;
}
.src-line { display: block; padding: 0 0.5rem; position: relative; }
.src-line .ln { color: var(--text-dim); display: inline-block; width: 2.5em; text-align: right; margin-right: 1em; user-select: none; }
.src-line.highlight { background: rgba(78, 201, 176, 0.1); border-left: 2px solid var(--green); }
.src-line.executing { background: rgba(220, 220, 170, 0.12); border-left: 2px solid var(--yellow); }
.src-line.executing .ln::before { content: '▶'; color: var(--yellow); position: absolute; left: 0.15rem; font-size: 10px; }
.src-kw { color: var(--blue); }
.src-type { color: var(--blue); }
.src-fn { color: var(--yellow); }
.src-str { color: var(--amber); }
.src-cmt { color: var(--comment); font-style: italic; }
.src-vuln { color: var(--red); text-decoration: underline wavy var(--red); }

/* Stack panel */
#stack-panel { grid-column: 2; grid-row: 1; }
#stack-viz { font-size: 12px; }

.stack-row {
  display: flex; align-items: center; padding: 2px 0;
  border-bottom: 1px solid rgba(255,255,255,0.03);
  transition: background 0.3s;
}
.stack-row.region-start { border-top: 1px solid var(--panel-border); }
.stack-addr { color: var(--text-dim); width: 8em; text-align: right; padding-right: 0.75em; flex-shrink: 0; font-size: 11px; }
.stack-bytes { display: flex; gap: 2px; flex-shrink: 0; }
.stack-byte {
  width: 2.2em; text-align: center; padding: 2px 0; border-radius: 2px;
  transition: all 0.2s; font-size: 12px;
}
.stack-byte.empty { color: var(--text-dim); }
.stack-ascii { color: var(--text-dim); padding-left: 0.75em; width: 5em; flex-shrink: 0; font-size: 11px; }
.stack-label { color: var(--text-dim); padding-left: 0.75em; font-size: 11px; white-space: nowrap; }

.region-buffer .stack-byte { background: rgba(78, 201, 176, 0.15); color: var(--green); }
.region-canary .stack-byte { background: rgba(197, 134, 192, 0.15); color: var(--purple); }
.region-ebp .stack-byte { background: rgba(86, 156, 214, 0.15); color: var(--blue); }
.region-ret .stack-byte { background: rgba(206, 145, 120, 0.15); color: var(--amber); }

.stack-byte.overflow {
  background: rgba(244, 71, 71, 0.3) !important; color: var(--red) !important;
  animation: pulse 0.6s ease;
}
.stack-byte.just-written { animation: flash 0.4s ease; }
.stack-byte.current {
  outline: 2px solid var(--yellow); outline-offset: -1px;
  animation: flash 0.3s ease;
}

@keyframes pulse { 0%,100% { opacity: 1; } 50% { opacity: 0.5; } }
@keyframes flash { 0% { background: rgba(255,255,255,0.4); } 100% {} }

/* Input panel */
#input-panel { grid-column: 1; grid-row: 2; }
#input-area { margin-bottom: 0.75rem; }
#input-area label { display: block; font-size: 11px; color: var(--text-dim); margin-bottom: 0.35rem; }
#payload-input {
  width: 100%; background: #0a0a0a; border: 1px solid var(--panel-border); color: var(--text);
  font-family: var(--font); font-size: 13px; padding: 0.5rem; resize: none; min-height: 2.5em;
}
#payload-input:focus { outline: none; border-color: var(--green); }
#payload-input::placeholder { color: var(--text-dim); }

.input-mode-toggle {
  display: flex; gap: 0.5rem; margin-bottom: 0.5rem;
}
.input-mode-toggle button {
  background: transparent; border: 1px solid var(--panel-border); color: var(--text-dim);
  font-family: var(--font); font-size: 11px; padding: 0.2rem 0.5rem; cursor: pointer;
}
.input-mode-toggle button.active { border-color: var(--green); color: var(--green); }

.controls {
  display: flex; gap: 0.5rem; flex-wrap: wrap;
}
.controls button {
  background: transparent; border: 1px solid var(--panel-border); color: var(--text);
  font-family: var(--font); font-size: 12px; padding: 0.35rem 1rem; cursor: pointer;
  transition: all 0.15s;
}
.controls button:hover:not(:disabled) { border-color: var(--green); color: var(--green); }
.controls button.primary { border-color: var(--green); color: var(--green); }
.controls button:disabled { opacity: 0.3; cursor: not-allowed; }

/* Payload builder */
#payload-builder {
  margin-top: 0.75rem; padding: 0.5rem; border: 1px solid var(--panel-border);
  font-size: 11px;
}
#payload-builder h4 { color: var(--text-dim); font-weight: normal; margin-bottom: 0.5rem; text-transform: uppercase; letter-spacing: 0.05em; }
.builder-row { display: flex; align-items: center; gap: 0.5rem; margin-bottom: 0.35rem; }
.builder-row label { color: var(--text-dim); width: 10em; }
.builder-row input {
  background: #0a0a0a; border: 1px solid var(--panel-border); color: var(--text);
  font-family: var(--font); font-size: 11px; padding: 0.25rem 0.4rem; width: 10em;
}
.builder-row input:focus { outline: none; border-color: var(--green); }
.builder-row .hint { color: var(--text-dim); font-size: 10px; }
#built-payload { color: var(--yellow); word-break: break-all; margin-top: 0.5rem; padding: 0.35rem; background: #0a0a0a; min-height: 1.5em; }

/* Hex calculator */
#hex-calc {
  margin-top: 0.75rem; padding: 0.5rem; border: 1px solid var(--panel-border);
  font-size: 11px;
}
#hex-calc h4 { color: var(--text-dim); font-weight: normal; margin-bottom: 0.5rem; text-transform: uppercase; letter-spacing: 0.05em; }
.calc-row { display: flex; align-items: center; gap: 0.35rem; margin-bottom: 0.35rem; flex-wrap: wrap; }
.calc-row input {
  background: #0a0a0a; border: 1px solid var(--panel-border); color: var(--text);
  font-family: var(--font); font-size: 12px; padding: 0.25rem 0.4rem; width: 10em;
}
.calc-row input:focus { outline: none; border-color: var(--green); }
.calc-op { color: var(--yellow); font-size: 14px; font-weight: bold; width: 1.5em; text-align: center; }
.calc-eq { color: var(--green); font-size: 14px; font-weight: bold; width: 1.5em; text-align: center; }
#calc-result {
  color: var(--green); font-size: 12px; font-weight: bold; padding: 0.25rem 0.4rem;
  background: #0a0a0a; border: 1px solid var(--green); min-width: 10em; display: inline-block;
}
.calc-hint { color: var(--text-dim); font-size: 10px; margin-top: 0.25rem; }

/* Symbols table */
#symbols-table { margin-top: 0.75rem; font-size: 11px; }
#symbols-table h4 { color: var(--text-dim); font-weight: normal; margin-bottom: 0.35rem; text-transform: uppercase; letter-spacing: 0.05em; }
.sym-row { display: flex; gap: 1rem; padding: 0.15rem 0; }
.sym-name { color: var(--yellow); width: 8em; }
.sym-addr { color: var(--amber); }
.sym-note { color: var(--text-dim); }
.sym-row.target .sym-name { color: var(--green); }
.sym-row.target .sym-addr { color: var(--green); }

/* Log panel */
#log-panel { grid-column: 2; grid-row: 2; }
#exec-log { font-size: 12px; line-height: 1.6; }
.log-entry { padding: 0.1rem 0; border-bottom: 1px solid rgba(255,255,255,0.02); }
.log-info { color: var(--text-dim); }
.log-action { color: var(--text); }
.log-warn { color: var(--amber); }
.log-error { color: var(--red); }
.log-success { color: var(--green); font-weight: bold; }
.log-addr { color: var(--amber); }
.log-label { color: var(--text-dim); font-size: 10px; display: inline; margin-left: 0.5em; }

/* Exercise description */
#exercise-desc {
  padding: 0.5rem 0.75rem; font-size: 12px; line-height: 1.5;
  border-bottom: 1px solid var(--panel-border); flex-shrink: 0;
  color: var(--text); background: rgba(78, 201, 176, 0.03);
}
#exercise-desc strong { color: var(--green); font-weight: normal; }

/* Sandbox controls */
.sandbox-controls {
  display: flex; gap: 1rem; flex-wrap: wrap; margin-bottom: 0.75rem;
  padding: 0.5rem; border: 1px solid var(--panel-border);
}
.sandbox-controls label { font-size: 11px; color: var(--text-dim); display: flex; align-items: center; gap: 0.4rem; }
.sandbox-controls input[type="range"] { width: 80px; }
.sandbox-controls input[type="checkbox"] { accent-color: var(--green); }

/* Success banner */
#success-banner {
  display: none; position: fixed; top: 50%; left: 50%; transform: translate(-50%, -50%);
  background: #111; border: 2px solid var(--green); padding: 2rem 3rem;
  text-align: center; z-index: 100; box-shadow: 0 0 60px rgba(78,201,176,0.2);
}
#success-banner.show { display: block; animation: fadeIn 0.3s ease; }
#success-banner h2 { color: var(--green); font-size: 16px; margin-bottom: 0.5rem; }
#success-banner p { color: var(--text); font-size: 13px; }
#success-banner button {
  margin-top: 1rem; background: transparent; border: 1px solid var(--green); color: var(--green);
  font-family: var(--font); font-size: 12px; padding: 0.35rem 1rem; cursor: pointer;
}
@keyframes fadeIn { from { opacity: 0; transform: translate(-50%, -50%) scale(0.95); } to { opacity: 1; transform: translate(-50%, -50%) scale(1); } }

/* CRT scanline overlay */
.crt::after {
  content: ''; position: fixed; top: 0; left: 0; width: 100%; height: 100%;
  background: repeating-linear-gradient(0deg, rgba(0,0,0,0.03) 0px, rgba(0,0,0,0.03) 1px, transparent 1px, transparent 3px);
  pointer-events: none; z-index: 1000;
}

/* Scrollbar */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--panel-bg); }
::-webkit-scrollbar-thumb { background: var(--panel-border); }

#gadget-table { margin-top: 0.75rem; font-size: 11px; }
#gadget-table h4 { color: var(--text-dim); font-weight: normal; margin-bottom: 0.35rem; text-transform: uppercase; letter-spacing: 0.05em; }
.gadget-row { display: flex; gap: 0.75rem; padding: 0.15rem 0; cursor: pointer; }
.gadget-row:hover { background: rgba(255,255,255,0.03); }
.gadget-addr { color: var(--amber); width: 9em; }
.gadget-asm { color: var(--text); }
.gadget-row.used { opacity: 0.5; }

#register-display {
  margin-top: 0.75rem; padding: 0.5rem; border: 1px solid var(--panel-border);
  font-size: 11px; display: grid; grid-template-columns: repeat(4, 1fr); gap: 0.25rem;
}
.reg-entry { display: flex; gap: 0.35rem; }
.reg-name { color: var(--blue); width: 3em; }
.reg-val { color: var(--amber); }
.reg-val.changed { color: var(--green); animation: flash 0.4s ease; }

#sigframe-builder {
  margin-top: 0.75rem; padding: 0.5rem; border: 1px solid var(--panel-border);
  font-size: 11px;
}
#sigframe-builder h4 { color: var(--text-dim); font-weight: normal; margin-bottom: 0.5rem; text-transform: uppercase; }
.sigframe-row { display: flex; align-items: center; gap: 0.5rem; margin-bottom: 0.25rem; }
.sigframe-row label { color: var(--blue); width: 5em; }
.sigframe-row input {
  background: #0a0a0a; border: 1px solid var(--panel-border); color: var(--text);
  font-family: var(--font); font-size: 11px; padding: 0.2rem 0.4rem; width: 10em;
}
#heap-viz { font-size: 12px; }
.heap-memory-strip { display: flex; flex-wrap: wrap; gap: 2px; margin-bottom: 1rem; padding: 0.5rem; border: 1px solid var(--panel-border); }
.heap-chunk { display: flex; flex-direction: column; border: 1px solid var(--panel-border); border-radius: 2px; overflow: hidden; min-width: 4em; }
.heap-chunk.allocated { border-color: var(--green); }
.heap-chunk.freed { border-color: var(--text-dim); opacity: 0.7; }
.heap-chunk.corrupted { border-color: var(--red); }
.heap-chunk.highlighted { outline: 2px solid var(--yellow); outline-offset: 1px; }
.heap-chunk-header { display: flex; font-size: 10px; padding: 2px 4px; background: rgba(255,255,255,0.05); }
.heap-chunk-header .prev-size { color: var(--text-dim); margin-right: 0.5em; }
.heap-chunk-header .size-field { color: var(--amber); }
.heap-chunk-header .flags { color: var(--purple); margin-left: 0.25em; }
.heap-chunk-data { padding: 4px; font-size: 11px; min-height: 1.5em; display: flex; flex-wrap: wrap; gap: 1px; }
.heap-chunk-data .byte { width: 2em; text-align: center; font-size: 11px; padding: 1px 0; border-radius: 1px; }
.heap-chunk-data .byte.allocated { color: var(--green); background: rgba(78,201,176,0.1); }
.heap-chunk-data .byte.freed { color: var(--text-dim); background: rgba(255,255,255,0.03); }
.heap-chunk-data .byte.pointer { color: var(--amber); background: rgba(206,145,120,0.15); }
.heap-chunk-data .byte.corrupted { color: var(--red); background: rgba(244,71,71,0.2); }
.heap-chunk-label { font-size: 10px; color: var(--text-dim); padding: 2px 4px; text-align: center; border-top: 1px solid var(--panel-border); }
.free-lists { margin-top: 0.75rem; font-size: 11px; }
.free-lists h4 { color: var(--text-dim); font-weight: normal; margin-bottom: 0.35rem; text-transform: uppercase; letter-spacing: 0.05em; }
.free-list-row { display: flex; align-items: center; gap: 0.25rem; padding: 0.15rem 0; flex-wrap: wrap; }
.free-list-name { color: var(--blue); width: 10em; }
.free-list-node { display: inline-flex; align-items: center; gap: 0.25rem; }
.free-list-addr { color: var(--amber); padding: 1px 4px; border: 1px solid var(--panel-border); border-radius: 2px; }
.free-list-arrow { color: var(--text-dim); }
.free-list-nil { color: var(--text-dim); font-style: italic; }
.func-ptr-table { margin-top: 0.75rem; font-size: 11px; }
.func-ptr-table h4 { color: var(--text-dim); font-weight: normal; margin-bottom: 0.35rem; text-transform: uppercase; letter-spacing: 0.05em; }
.func-ptr-row { display: flex; gap: 0.75rem; padding: 0.15rem 0; }
.func-ptr-name { color: var(--yellow); width: 10em; }
.func-ptr-val { color: var(--amber); }
.func-ptr-val.overwritten { color: var(--red); animation: flash 0.4s ease; }
.heap-top-chunk { border: 1px dashed var(--text-dim); border-radius: 2px; padding: 4px 8px; font-size: 10px; color: var(--text-dim); text-align: center; flex: 1; min-width: 4em; }
</style>
</head>
<body class="crt">
<div id="app">
  <header>
    <h1>// MEMORY CORRUPTION LAB</h1>
    <nav id="exercise-nav"></nav>
    <div id="badges"></div>
  </header>
  <main>
    <div class="panel" id="source-panel">
      <div class="panel-hdr">source.c</div>
      <div id="exercise-desc"></div>
      <div class="panel-body"><div id="source-code"></div></div>
    </div>
    <div class="panel" id="stack-panel">
      <div class="panel-hdr">stack <span id="stack-info"></span></div>
      <div class="panel-body"><div id="stack-viz"></div><div id="heap-viz"></div></div>
    </div>
    <div class="panel" id="input-panel">
      <div class="panel-hdr">input</div>
      <div class="panel-body">
        <div id="input-area"></div>
        <div id="payload-builder" style="display:none"></div>
        <div id="hex-calc" style="display:none"></div>
        <div id="symbols-table" style="display:none"></div>
        <div id="gadget-table" style="display:none"></div>
        <div id="register-display" style="display:none"></div>
        <div id="sigframe-builder" style="display:none"></div>
      </div>
    </div>
    <div class="panel" id="log-panel">
      <div class="panel-hdr">execution log</div>
      <div class="panel-body"><div id="exec-log"></div></div>
    </div>
  </main>
</div>
<div id="success-banner">
  <h2 id="success-title"></h2>
  <p id="success-msg"></p>
  <button onclick="dismissSuccess()">Continue</button>
</div>

<script>
// ──────────────────────────────────────────────
// Stack Simulator
// ──────────────────────────────────────────────
class StackSim {
  constructor(bufSize, retAddr, savedEbp, baseAddr, useCanary) {
    this.bufSize = bufSize;
    this.canarySize = useCanary ? 4 : 0;
    this.ebpSize = 4;
    this.retSize = 4;
    this.totalSize = bufSize + this.canarySize + this.ebpSize + this.retSize;
    this.baseAddr = baseAddr || 0xbfff0100;
    this.memory = new Uint8Array(this.totalSize);
    this.written = new Uint8Array(this.totalSize);
    this.overflowAt = new Uint8Array(this.totalSize);
    this.inputLen = 0;
    this.useCanary = !!useCanary;

    this.origRetAddr = retAddr;
    this.origSavedEbp = savedEbp;
    this.canaryValue = 0;
    if (this.useCanary) {
      this.canaryValue = (Math.random() * 0xffffffff) >>> 0;
      this._writeLE(this.bufSize, this.canaryValue, 4);
    }
    this._writeLE(this.bufSize + this.canarySize, savedEbp, 4);
    this._writeLE(this.bufSize + this.canarySize + 4, retAddr, 4);
    this.written.fill(0);
  }

  _writeLE(offset, value, size) {
    for (let i = 0; i < size; i++) {
      this.memory[offset + i] = (value >>> (i * 8)) & 0xff;
    }
  }

  _readLE(offset, size) {
    let v = 0;
    for (let i = size - 1; i >= 0; i--) {
      v = (v * 256) + this.memory[offset + i];
    }
    return v >>> 0;
  }

  writeInput(bytes) {
    this.inputLen = bytes.length;
    if (this.useCanary) this._writeLE(this.bufSize, this.canaryValue, 4);
    this._writeLE(this.bufSize + this.canarySize, this.origSavedEbp, 4);
    this._writeLE(this.bufSize + this.canarySize + 4, this.origRetAddr, 4);
    this.written.fill(0);
    this.overflowAt.fill(0);

    for (let i = 0; i < bytes.length && i < this.totalSize; i++) {
      this.memory[i] = bytes[i];
      this.written[i] = 1;
      if (i >= this.bufSize) {
        this.overflowAt[i] = 1;
      }
    }
  }

  resetForInput() {
    if (this.useCanary) this._writeLE(this.bufSize, this.canaryValue, 4);
    this._writeLE(this.bufSize + this.canarySize, this.origSavedEbp, 4);
    this._writeLE(this.bufSize + this.canarySize + 4, this.origRetAddr, 4);
    this.written.fill(0);
    this.overflowAt.fill(0);
    this.inputLen = 0;
    this.hlStart = -1;
    this.hlEnd = -1;
  }

  clearBlank() {
    this.memory.fill(0);
    this.written.fill(0);
    this.overflowAt.fill(0);
    this.hlStart = -1;
    this.hlEnd = -1;
  }

  writeWord(offset, bytes) {
    for (let i = 0; i < bytes.length && (offset + i) < this.totalSize; i++) {
      this.memory[offset + i] = bytes[i];
      this.written[offset + i] = 1;
      if ((offset + i) >= this.bufSize) this.overflowAt[offset + i] = 1;
    }
    this.inputLen = Math.max(this.inputLen, offset + bytes.length);
    this.hlStart = offset;
    this.hlEnd = offset + bytes.length;
  }

  markRegion(start, end) {
    for (let i = start; i < end && i < this.totalSize; i++) this.written[i] = 1;
    this.hlStart = start;
    this.hlEnd = end;
  }

  clearHighlight() { this.hlStart = -1; this.hlEnd = -1; }

  getRetAddr() { return this._readLE(this.bufSize + this.canarySize + 4, 4); }
  getSavedEbp() { return this._readLE(this.bufSize + this.canarySize, 4); }
  getCanary() { return this.useCanary ? this._readLE(this.bufSize, 4) : null; }
  canaryIntact() { return !this.useCanary || this.getCanary() === this.canaryValue; }

  regionOf(byteIndex) {
    if (byteIndex < this.bufSize) return 'buffer';
    if (this.useCanary && byteIndex < this.bufSize + this.canarySize) return 'canary';
    if (byteIndex < this.bufSize + this.canarySize + this.ebpSize) return 'ebp';
    if (byteIndex < this.bufSize + this.canarySize + this.ebpSize + this.retSize) return 'ret';
    return 'ret'; // extra bytes past ret (for ret2libc/ROP/SROP payloads)
  }
}

// ──────────────────────────────────────────────
// HeapSim — glibc-like heap allocator simulation
// ──────────────────────────────────────────────
class HeapSim {
  constructor(size = 1024) {
    this.memorySize = size;
    this.memory = new Uint8Array(size);
    this.written = new Uint8Array(size);
    this.highlight = { start: -1, end: -1 };
    this.chunks = new Map(); // addr → {size, allocated, dataStart}
    this.HEADER_SIZE = 8;   // prev_size(4) + size(4)
    this.MIN_CHUNK = 16;    // header + at least 8 data (or fd+bk)
    this.tcache = {};        // size → [addr, ...] (max 7 per bin)
    this.fastbins = {};      // size → [addr, ...]
    this.unsorted = [];      // [addr, ...]
    this.topAddr = 0;
    this.topSize = size;
    this.funcPtrs = {};
    this.mainArena = 0x0804b100;
    this.baseAddr = 0x08050000;
  }

  _writeLE(offset, value, size) {
    for (let i = 0; i < size; i++) {
      this.memory[offset + i] = (value >>> (i * 8)) & 0xff;
    }
  }

  _readLE(offset, size) {
    let v = 0;
    for (let i = size - 1; i >= 0; i--) {
      v = (v * 256) + this.memory[offset + i];
    }
    return v >>> 0;
  }

  _alignSize(requested) {
    // Add header, align to 8 bytes, enforce minimum
    let total = requested + this.HEADER_SIZE;
    total = (total + 7) & ~7;
    if (total < this.MIN_CHUNK) total = this.MIN_CHUNK;
    return total;
  }

  malloc(requested) {
    const chunkSize = this._alignSize(requested);
    const dataSize = chunkSize - this.HEADER_SIZE;

    // 1. Check tcache
    if (this.tcache[chunkSize] && this.tcache[chunkSize].length > 0) {
      const addr = this.tcache[chunkSize].pop();
      const chunk = this.chunks.get(addr);
      if (chunk) {
        chunk.allocated = true;
        this._writeChunkHeader(addr, chunkSize, true);
        return { addr: addr, dataAddr: addr + this.HEADER_SIZE, dataSize: dataSize };
      }
    }

    // 2. Check fastbin (for sizes <= 64)
    if (chunkSize <= 64 && this.fastbins[chunkSize] && this.fastbins[chunkSize].length > 0) {
      const addr = this.fastbins[chunkSize].pop();
      const chunk = this.chunks.get(addr);
      if (chunk) {
        chunk.allocated = true;
        this._writeChunkHeader(addr, chunkSize, true);
        return { addr: addr, dataAddr: addr + this.HEADER_SIZE, dataSize: dataSize };
      }
    }

    // 3. Check unsorted bin
    for (let i = 0; i < this.unsorted.length; i++) {
      const addr = this.unsorted[i];
      const chunk = this.chunks.get(addr);
      if (chunk && chunk.size >= chunkSize) {
        this.unsorted.splice(i, 1);
        chunk.allocated = true;
        this._writeChunkHeader(addr, chunk.size, true);
        return { addr: addr, dataAddr: addr + this.HEADER_SIZE, dataSize: chunk.size - this.HEADER_SIZE };
      }
    }

    // 4. Carve from top chunk
    if (this.topSize >= chunkSize) {
      const addr = this.topAddr;
      this.topAddr += chunkSize;
      this.topSize -= chunkSize;
      this.chunks.set(addr, { size: chunkSize, allocated: true, dataStart: addr + this.HEADER_SIZE });
      this._writeChunkHeader(addr, chunkSize, true);
      return { addr: addr, dataAddr: addr + this.HEADER_SIZE, dataSize: dataSize };
    }

    return null; // out of memory
  }

  free(addr) {
    // addr is the chunk start (header), not the data pointer
    // If caller passes data pointer, adjust
    let chunkAddr = addr;
    if (!this.chunks.has(addr) && this.chunks.has(addr - this.HEADER_SIZE)) {
      chunkAddr = addr - this.HEADER_SIZE;
    }
    const chunk = this.chunks.get(chunkAddr);
    if (!chunk || !chunk.allocated) return false;

    chunk.allocated = false;
    const chunkSize = chunk.size;
    const dataStart = chunkAddr + this.HEADER_SIZE;

    // Mark chunk as freed in header (clear in-use bit)
    this._writeChunkHeader(chunkAddr, chunkSize, false);

    // 1. Try tcache first (max 7 per bin)
    if (!this.tcache[chunkSize]) this.tcache[chunkSize] = [];
    if (this.tcache[chunkSize].length < 7) {
      // Write fd pointer (points to previous tcache entry or 0)
      const prevFd = this.tcache[chunkSize].length > 0
        ? this.tcache[chunkSize][this.tcache[chunkSize].length - 1] + this.HEADER_SIZE
        : 0;
      this._writeLE(dataStart, prevFd, 4);
      this.written[dataStart] = 1;
      this.written[dataStart + 1] = 1;
      this.written[dataStart + 2] = 1;
      this.written[dataStart + 3] = 1;
      this.tcache[chunkSize].push(chunkAddr);
      return true;
    }

    // 2. Fastbin (if size <= 64)
    if (chunkSize <= 64) {
      if (!this.fastbins[chunkSize]) this.fastbins[chunkSize] = [];
      const prevFd = this.fastbins[chunkSize].length > 0
        ? this.fastbins[chunkSize][this.fastbins[chunkSize].length - 1] + this.HEADER_SIZE
        : 0;
      this._writeLE(dataStart, prevFd, 4);
      this.written[dataStart] = 1;
      this.written[dataStart + 1] = 1;
      this.written[dataStart + 2] = 1;
      this.written[dataStart + 3] = 1;
      this.fastbins[chunkSize].push(chunkAddr);
      return true;
    }

    // 3. Unsorted bin
    const prevFd = this.unsorted.length > 0
      ? this.unsorted[this.unsorted.length - 1] + this.HEADER_SIZE
      : 0;
    this._writeLE(dataStart, prevFd, 4);
    this.written[dataStart] = 1;
    this.written[dataStart + 1] = 1;
    this.written[dataStart + 2] = 1;
    this.written[dataStart + 3] = 1;
    this.unsorted.push(chunkAddr);
    return true;
  }

  _writeChunkHeader(addr, size, inUse) {
    // prev_size (4 bytes) — leave as-is for now
    // size field (4 bytes): actual size | PREV_INUSE flag (bit 0)
    const sizeField = inUse ? (size | 1) : (size & ~1);
    this._writeLE(addr + 4, sizeField, 4);
  }

  write(offset, bytes) {
    for (let i = 0; i < bytes.length && (offset + i) < this.memorySize; i++) {
      this.memory[offset + i] = bytes[i];
      this.written[offset + i] = 1;
    }
  }

  read(offset, size) {
    const result = [];
    for (let i = 0; i < size && (offset + i) < this.memorySize; i++) {
      result.push(this.memory[offset + i]);
    }
    return result;
  }

  getChunksForDisplay() {
    const sorted = Array.from(this.chunks.entries())
      .sort((a, b) => a[0] - b[0])
      .map(([addr, info]) => ({
        addr: addr,
        size: info.size,
        allocated: info.allocated,
        dataStart: addr + this.HEADER_SIZE,
        dataSize: info.size - this.HEADER_SIZE,
        highlighted: addr >= this.highlight.start && addr < this.highlight.end
      }));
    return sorted;
  }

  getFreeLists() {
    return {
      tcache: { ...this.tcache },
      fastbins: { ...this.fastbins },
      unsorted: [...this.unsorted]
    };
  }

  markRegion(start, end) {
    this.highlight = { start: start, end: end };
  }

  clearHighlight() {
    this.highlight = { start: -1, end: -1 };
  }
}

// ──────────────────────────────────────────────
// Hex/address helpers
// ──────────────────────────────────────────────
function hex8(v) { return '0x' + (v >>> 0).toString(16).padStart(8, '0'); }
function hex2(v) { return (v & 0xff).toString(16).padStart(2, '0'); }
function toAscii(v) { return (v >= 0x20 && v <= 0x7e) ? String.fromCharCode(v) : '.'; }
function addrToLE(addrStr) {
  let v = parseInt(addrStr, 16);
  if (isNaN(v)) return null;
  return [(v >>> 0) & 0xff, (v >>> 8) & 0xff, (v >>> 16) & 0xff, (v >>> 24) & 0xff];
}
function hexStrToBytes(str) {
  const clean = str.replace(/\s+/g, '').replace(/^0x/i, '');
  const bytes = [];
  for (let i = 0; i < clean.length; i += 2) {
    const b = parseInt(clean.substr(i, 2), 16);
    if (isNaN(b)) break;
    bytes.push(b);
  }
  return bytes;
}
function strToBytes(str) {
  return Array.from(str).map(c => c.charCodeAt(0) & 0xff);
}

// ──────────────────────────────────────────────
// State
// ──────────────────────────────────────────────
const state = {
  currentEx: 0,
  sim: null,
  completed: new Set(),
  logMessages: [],
  inputMode: 'text',
  stepIndex: 0,
  symbols: {},
  aslrBase: 0,
  running: false,
  execSteps: null,
  execIndex: 0,
};

// ──────────────────────────────────────────────
// Exercises
// ──────────────────────────────────────────────
const BASE_SYMBOLS = {
  main:   0x08048000,
  vuln:   0x08048054,
  win:    0x08048150,
  normal: 0x080480a0,
  system: 0x08048200,
  binsh:  0x08049300,
};

function retAddrInMain() { return (state.symbols.main || BASE_SYMBOLS.main) + 0x25; }

const EXERCISES = [
  {
    unit: 1,
    title: '01: The Stack Frame',
    desc: 'Watch how a function call sets up memory. Click <strong>Step</strong> to see each piece get placed on the stack — the computer saves where to go back to (return address), saves a bookmark to the previous frame, then makes room for local variables.',
    code: [
      { text: '#include <stdio.h>', cls: '' },
      { text: '', cls: '' },
      { text: 'void vuln() {', cls: '', fn: true },
      { text: '    char buf[16];', cls: 'highlight' },
      { text: '    // memory layout on the stack:', cls: 'cmt' },
      { text: '    // [buf 16 bytes] [saved bookmark] [go-back address]', cls: 'cmt' },
      { text: '}', cls: '' },
      { text: '', cls: '' },
      { text: 'int main() {', cls: '' },
      { text: '    vuln();', cls: 'highlight' },
      { text: '    return 0;', cls: '' },
      { text: '}', cls: '' },
    ],
    mode: 'step',
    bufSize: 16,
    showSymbols: false,
    showBuilder: false,
    aslr: false,
    steps: [
      { region: 'none', log: ['info', 'main() is about to call vuln()...'] },
      { region: 'ret', log: ['action', 'The computer saves the go-back address so it knows where to return after vuln() finishes'] },
      { region: 'ebp', log: ['action', 'Save a bookmark to the previous frame (saved EBP) — used to clean up later'] },
      { region: 'buffer', log: ['action', 'Make room for buf[] — 16 bytes of space for our input'] },
      { region: 'all', log: ['info', 'Done! The stack now has: our buffer (green), the saved bookmark (blue), and the go-back address (orange). The go-back address is the key — it controls where the program goes next.'] },
    ],
    check() { return false; },
  },
  {
    unit: 1,
    title: '02: The Overflow',
    desc: 'This function reads your input with <strong>gets()</strong> — a dangerous function that doesn\'t check how much you type. Fill the 16-byte buffer, then <strong>keep typing</strong>. Watch what happens when your input spills into the saved bookmark and go-back address above it.',
    code: [
      { text: '#include <stdio.h>', cls: '' },
      { text: '', cls: '' },
      { text: 'void vuln() {', cls: '', fn: true },
      { text: '    char buf[16];', cls: '' },
      { text: '    gets(buf);', cls: 'highlight vuln' },
      { text: '    printf("You entered: %s\\n", buf);', cls: '' },
      { text: '}', cls: '' },
      { text: '', cls: '' },
      { text: 'int main() {', cls: '' },
      { text: '    printf("Enter your name: ");', cls: '' },
      { text: '    vuln();', cls: '' },
      { text: '    return 0;', cls: '' },
      { text: '}', cls: '' },
    ],
    mode: 'input-text',
    bufSize: 16,
    showSymbols: false,
    showBuilder: false,
    aslr: false,
    check(sim) {
      const ret = sim.getRetAddr();
      return ret !== sim.origRetAddr && !Object.values(state.symbols).includes(ret);
    },
    winTitle: 'Crash! Segmentation Fault',
    winMsg: 'The program crashed because you overwrote the go-back address with garbage. The computer tried to jump to a nonsense location and exploded. Nice work — in exercise 3, you\'ll control WHERE it jumps instead of just crashing it.',
  },
  {
    unit: 1,
    title: '03: Hijack Execution',
    desc: 'Now instead of crashing, make the program jump to <strong>win()</strong>. Use the payload builder to craft your input: 16 bytes of filler (fills the buffer), 4 bytes of junk (overwrites saved bookmark), then the address of win() written <strong>backwards</strong> (little-endian — the least significant byte goes first).',
    code: [
      { text: '#include <stdio.h>', cls: '' },
      { text: '#include <stdlib.h>', cls: '' },
      { text: '', cls: '' },
      { text: 'void win() {', cls: '' },
      { text: '    printf("FLAG{you_own_the_eip}\\n");', cls: '' },
      { text: '    // you redirected execution here!', cls: 'cmt' },
      { text: '}', cls: '' },
      { text: '', cls: '' },
      { text: 'void vuln() {', cls: '', fn: true },
      { text: '    char buf[16];', cls: '' },
      { text: '    gets(buf);', cls: 'highlight vuln' },
      { text: '}', cls: '' },
      { text: '', cls: '' },
      { text: 'int main() {', cls: '' },
      { text: '    vuln();', cls: '' },
      { text: '    return 0;', cls: '' },
      { text: '}', cls: '' },
    ],
    mode: 'input-hex',
    bufSize: 16,
    showSymbols: true,
    showBuilder: true,
    aslr: false,
    check(sim) {
      return sim.getRetAddr() === state.symbols.win;
    },
    winTitle: 'FLAG{you_own_the_eip}',
    winMsg: 'You made the program run a function it was never supposed to call! In a real attack, this is how hackers take control of a computer — they overwrite the go-back address to run whatever they want.',
  },
  {
    unit: 1,
    title: '04: Randomized Addresses',
    desc: 'Now the computer shuffles where everything is in memory each time the program runs (<strong>ASLR</strong>). Your old address for win() won\'t work anymore! But the program accidentally prints where <strong>main()</strong> is. Since win() is always <strong>+0x150</strong> bytes after main(), you can do the math. Use the hex calculator to add the leaked address + offset.',
    code: [
      { text: '#include <stdio.h>', cls: '' },
      { text: '', cls: '' },
      { text: 'void win() {', cls: '' },
      { text: '    printf("FLAG{aslr_defeated}\\n");', cls: '' },
      { text: '}', cls: '' },
      { text: '', cls: '' },
      { text: 'void vuln() {', cls: '', fn: true },
      { text: '    char buf[16];', cls: '' },
      { text: '    // info leak — but not the function we want', cls: 'cmt' },
      { text: '    printf("DEBUG: main=%p\\n", main);', cls: 'highlight' },
      { text: '    gets(buf);', cls: 'highlight vuln' },
      { text: '}', cls: '' },
      { text: '', cls: '' },
      { text: 'int main() {', cls: '' },
      { text: '    vuln();', cls: '' },
      { text: '    return 0;', cls: '' },
      { text: '}', cls: '' },
    ],
    mode: 'input-hex',
    bufSize: 16,
    showSymbols: false,
    showBuilder: true,
    showCalc: true,
    aslr: true,
    check(sim) {
      return sim.getRetAddr() === state.symbols.win;
    },
    winTitle: 'FLAG{aslr_defeated}',
    winMsg: 'Even though the addresses were randomized, you figured out win()\'s address by reading the leaked main() address and doing simple math. This is exactly how real hackers beat ASLR — find one leaked address, calculate the rest.',
  },
  {
    unit: 1,
    title: '05: The Tripwire',
    desc: 'The program now places a secret value (a <strong>stack canary</strong>) between your buffer and the important stuff above it — like a tripwire. If you overwrite it, the program catches you and aborts. But there\'s a bug that leaks the secret value. Put the correct canary bytes in your payload at the right spot to sneak past the tripwire.',
    code: [
      { text: '#include <stdio.h>', cls: '' },
      { text: '', cls: '' },
      { text: 'void win() {', cls: '' },
      { text: '    printf("FLAG{canary_bypassed}\\n");', cls: '' },
      { text: '}', cls: '' },
      { text: '', cls: '' },
      { text: 'void vuln() {', cls: '', fn: true },
      { text: '    char buf[16];', cls: '' },
      { text: '    // format string leak — prints stack contents', cls: 'cmt' },
      { text: '    printf(buf);', cls: 'highlight' },
      { text: '    gets(buf);', cls: 'highlight vuln' },
      { text: '}', cls: '' },
      { text: '', cls: '' },
      { text: 'int main() {', cls: '' },
      { text: '    vuln();', cls: '' },
      { text: '    return 0;', cls: '' },
      { text: '}', cls: '' },
    ],
    mode: 'input-hex',
    bufSize: 16,
    showSymbols: true,
    showBuilder: true,
    aslr: false,
    canary: true,
    check(sim) {
      return sim.canaryIntact() && sim.getRetAddr() === state.symbols.win;
    },
    winTitle: 'FLAG{canary_bypassed}',
    winMsg: 'You read the leaked secret value and carefully placed it in your payload so the tripwire stayed intact — while still overwriting the go-back address. Sneaky! This is how real attackers bypass stack canaries.',
  },
  {
    title: '06: Integer Overflow',
    unit: 2,
    desc: 'The program adds a header size (64) to your input length. But what happens when your number is so big that the addition <strong>wraps around</strong> past the maximum value? The buffer ends up tiny, but the program still reads your full input — overflow!',
    code: [
      { text: '#include <stdio.h>', cls: '' },
      { text: '', cls: '' },
      { text: 'void win() { printf("FLAG\\n"); }', cls: '' },
      { text: '', cls: '' },
      { text: 'void process(unsigned int user_len) {', cls: '', fn: true },
      { text: '    unsigned int total = user_len + 64;', cls: 'highlight vuln' },
      { text: '    char buf[total];', cls: '' },
      { text: '    read_input(buf, user_len);', cls: 'highlight' },
      { text: '}', cls: '' },
      { text: '', cls: '' },
      { text: 'int main() {', cls: '' },
      { text: '    unsigned int len;', cls: '' },
      { text: '    scanf("%u", &len);', cls: '' },
      { text: '    process(len);', cls: '' },
      { text: '    return 0;', cls: '' },
      { text: '}', cls: '' },
    ],
    mode: 'input-int-overflow',
    vizMode: 'stack',
    bufSize: 16,
    showSymbols: true,
    showBuilder: true,
    aslr: false,
    intOverflow: true,
    headerSize: 64,
    check(sim) {
      return sim.getRetAddr() === state.symbols.win;
    },
    winTitle: 'FLAG{integer_wrap}',
    winMsg: 'The math wrapped around! A huge number + 64 became a tiny number, so the buffer was too small. Your input overflowed it and hijacked the go-back address. This is how integer overflows lead to memory corruption.',
  },
  {
    title: '07: Format String: Reading',
    unit: 2,
    desc: 'The program passes your input directly to <strong>printf()</strong> as the format string. Normally printf expects a fixed string like "hello %s". But if YOU control the format string, you can use <strong>%x</strong> to read values from the stack — like a secret password stored in memory.',
    code: [
      { text: '#include <stdio.h>', cls: '' },
      { text: '', cls: '' },
      { text: 'void vuln() {', cls: '', fn: true },
      { text: '    int secret = 0xCAFEBABE;', cls: '' },
      { text: '    char buf[64];', cls: '' },
      { text: '    fgets(buf, 64, stdin);', cls: '' },
      { text: '    printf(buf);', cls: 'highlight vuln' },
      { text: '    // BUG: user input IS the format string!', cls: 'cmt' },
      { text: '}', cls: '' },
      { text: '', cls: '' },
      { text: 'int main() {', cls: '' },
      { text: '    vuln();', cls: '' },
      { text: '    return 0;', cls: '' },
      { text: '}', cls: '' },
    ],
    mode: 'input-fmt-read',
    vizMode: 'stack',
    bufSize: 64,
    showSymbols: false,
    showBuilder: false,
    aslr: false,
    fmtRead: true,
    secretValue: 0xCAFEBABE,
    secretOffset: 3,
    check(sim) {
      return state.fmtLeakedSecret === true;
    },
    winTitle: 'Secret Leaked!',
    winMsg: 'You used %x to walk up the stack and read the secret value. In real exploits, this technique leaks canaries, return addresses, and heap pointers — anything stored on the stack.',
  },

  // ── Exercise 08: Format String Writing (%n) ──
  {
    title: '08: Format String: Writing',
    unit: 2,
    desc: 'The <strong>%n</strong> format specifier doesn\'t print — it <strong>writes</strong>. It stores the number of characters printed so far into a memory address on the stack. Put the right address in your input, advance with %x, then %n writes to it. Change <strong>authorized</strong> from 0 to anything else.',
    code: [
      { text: '#include <stdio.h>', cls: '' },
      { text: '', cls: '' },
      { text: 'void win() { printf("FLAG\\n"); }', cls: '' },
      { text: '', cls: '' },
      { text: 'int authorized = 0;  // at 0x0804a020', cls: 'highlight' },