Merge pull request #178 from CoinFabrik/172-add-vulnerability-documen…

…tation-for-6-unprotected-update-current-contract-wasm

172-add-vulnerability-documentation-for-6-unprotected-update-current-contract-wasm

docs/docs/vulnerabilities/6-unprotected-update-current-contract-wasm.md

@@ -0,0 +1,59 @@
+# Unprotected update current contract wasm
+
+## Description
+
+- Vulnerability Category: `Authorization`
+- Vulnerability Severity: `Critical`
+- Detectors: [`unprotected-update-current-contract-wasm`](https://github.com/CoinFabrik/scout-soroban/tree/main/detectors/unprotected-update-current-contract-wasm)
+- Test Cases: [`unprotected-update-current-contract-wasm-1`](https://github.com/CoinFabrik/scout-soroban/tree/main/test-cases/unprotected-update-current-contract-wasm/unprotected-update-current-contract-wasm-1) [`unprotected-update-current-contract-wasm-2`](https://github.com/CoinFabrik/scout-soroban/tree/main/test-cases/unprotected-update-current-contract-wasm/unprotected-update-current-contract-wasm-2)
+
+It warns you if `update_current_contract_wasm()` function is called without a previous check of the address of the caller. If users are allowed to call `update_current_contract_wasm()`, they can intentionally modify the contract behaviour, leading to the loss of all associated data/tokens and functionalities given by this contract or by others that depend on it.
+
+## Exploit Scenario
+
+Consider the following `Soroban` contract:
+
+```rust
+#[contractimpl]
+impl UpgradeableContract {
+    pub fn init(e: Env, admin: Address) {
+        e.storage().instance().set(&DataKey::Admin, &admin);
+    }
+
+    pub fn version() -> u32 {
+        1
+    }
+
+    pub fn upgrade(e: Env, new_wasm_hash: BytesN<32>) {
+        e.deployer().update_current_contract_wasm(new_wasm_hash);
+    }
+}
+``` 
+This contract allows upgrades through the `update_current_contract_wasm` function. If just anyone can call this function, they could modify the contract behaviour.
+
+The vulnerable code example can be found [`here`](https://github.com/CoinFabrik/scout-soroban/tree/main/test-cases/unprotected-update-current-contract-wasm/unprotected-update-current-contract-wasm-1/vulnerable-example).
+
+## Remediation
+
+To prevent this, the function should be restricted to administrators or authorized users only.
+
+```rust
+#[contractimpl]
+impl UpgradeableContract {
+    pub fn init(e: Env, admin: Address) {
+        e.storage().instance().set(&DataKey::Admin, &admin);
+    }
+
+    pub fn version() -> u32 {
+        1
+    }
+
+    pub fn upgrade(e: Env, new_wasm_hash: BytesN<32>) {
+        let admin: Address = e.storage().instance().get(&DataKey::Admin).unwrap();
+        admin.require_auth();
+
+        e.deployer().update_current_contract_wasm(new_wasm_hash);
+    }
+}
+```
+The remediated code example can be found [`here`](https://github.com/CoinFabrik/scout-soroban/tree/main/test-cases/unprotected-update-current-contract-wasm/unprotected-update-current-contract-wasm-1/remediated-example).