# Audit Summary and Attack Simulation

## Durianfun V4.5 final audit report

Nacho Audit completed a full review of:

* `DurianAMMV45.sol`
* `BondingCurveMarketV45.sol`
* `DuriandotfunFactoryV45.sol`
* `DurianToken.sol`

Review parameters:

* Scope: 14-point security and economic review
* Compiler: Solidity `0.8.24`, `viaIR`, optimizer `200`
* Methods: manual review, invariant checks, mathematical validation, on-chain simulation
* Finalized: `2026-04-14`

### Durianfun V4.5 audit snapshot

*by Nacho Audit*

> **Target:** `DurianAMMV45.sol` · `BondingCurveMarketV45.sol` · `DuriandotfunFactoryV45.sol` · `DurianToken.sol`\
> **Scope:** 14-point security and economic review\
> **Compiler:** Solidity `0.8.24`, `viaIR`, optimizer `200`\
> **Approach:** manual review · invariant checks · mathematical validation · on-chain simulation\
> **Finalized:** `2026-04-14`

***

### Score Summary

| Area                    | Score         |
| ----------------------- | ------------- |
| **Security**            | **9.9 / 10**  |
| **Decentralization**    | **10.0 / 10** |
| **Code Quality**        | **9.8 / 10**  |
| **Economic Robustness** | **9.9 / 10**  |
| **Immutability**        | **10.0 / 10** |
| **Access Control**      | **9.8 / 10**  |
| **MEV Resistance**      | **9.8 / 10**  |
| **Gas Efficiency**      | **9.6 / 10**  |
| **Upgrade Safety**      | **10.0 / 10** |

#### Composite: **9.85 / 10**

***

### Findings Summary

| Severity      | Count | Status               |
| ------------- | ----- | -------------------- |
| Critical      | **0** | —                    |
| High          | **0** | —                    |
| Medium        | **5** | **All fixed**        |
| Low           | **2** | Acceptable by design |
| Informational | **3** | Noted                |

**Legend:** Critical · High · Medium · Low · Informational

***

### Why Durianfun V4.5 stands out

Durianfun combines a bonding curve with a permanent AMM. The handoff is automatic and price-aligned. That removes the usual break between price discovery and live liquidity.

#### Architecture — bonding curve to AMM graduation

Most launchpads use one model:

* **Pure bonding curves** can create a sharp pricing break at maturity.
* **Pure AMMs** skip an orderly price-discovery phase.

Durianfun uses one atomic transition. A token moves from the bonding curve into a sealed AMM pool at a price aligned with the curve's terminal state.

```
Pre-graduation:  Bonding Curve (x·y=k virtual) — price discovery
                       │
                       │  ← at threshold, in one tx:
                       │     • curve disabled permanently
                       │     • AMM deployed atomically
                       │     • reserves seeded at price parity
                       │     • 10-block cooldown starts
                       ▼
Post-graduation: Sealed AMM (x·y=k real) — permanent liquidity
```

No manual trigger. No admin switch. No pricing cliff. The transition is deterministic and fully on-chain.

#### Why user funds are protected

| Risk               | Typical exposure                   | Durianfun V4.5                                          |
| ------------------ | ---------------------------------- | ------------------------------------------------------- |
| LP removal         | Admin withdraws liquidity          | Impossible — no `removeLiquidity`, `burn`, or `mint`    |
| Fee abuse          | Owner raises fees aggressively     | Impossible — 2% cap in bytecode; AMM fee is `constant`  |
| Upgrade risk       | Proxy changes logic                | Impossible — no proxy or `delegatecall`                 |
| Hidden mint        | Extra supply minted later          | Impossible — token exposes no `mint()`                  |
| Freeze / blacklist | Transfers can be blocked           | Impossible — no freeze, blacklist, or transfer tax      |
| Graduation DOS     | Malicious wallet blocks graduation | Impossible — 30k cap plus treasury fallback             |
| Fee-send griefing  | Treasury can consume all gas       | Impossible — 50k cap on fee transfers                   |
| Reentrancy         | External callback drain            | Impossible — `nonReentrant` on entry points             |
| Overflow           | Arithmetic bug                     | Impossible — Solidity `0.8.24` checked math             |
| Flash manipulation | Borrow-manipulate-repay cycle      | No native flash path on KUB; round trip still pays 0.4% |
| Graduation sniping | Bot targets fresh AMM              | 10-block cooldown enforced on-chain                     |
| Creator privilege  | Creator retains admin power        | Creator is `immutable` and has no admin rights          |

These controls live in contract logic, not only in the UI. If the site is offline, the contracts remain callable on-chain.

#### Protection during the bonding phase

The bonding phase carries the highest execution risk. V4.5 applies layered controls.

**For traders:**

* **Slippage checks** — every buy and sell requires `minOut`.
* **Overshoot refund** — threshold overflow refunds atomically in the same transaction.
* **Transparent pricing** — next price is computable on-chain, with no oracle dependency.
* **Deterministic ordering** — no whitelist and no privileged route.

**For creators:**

* **Creation cost** — `0.1 KUB` reduces bot spam.
* **Immutable attribution** — creator record is fixed at launch.
* **Direct rebate** — `0.167%` paid per trade, with no claim flow.
* **Graduation bonus** — `10 KUB` paid automatically with fallback protection.

**For the system:**

* **Single-pass graduation** — one buyer triggers it, others revert cleanly.
* **State-before-external** — accounting updates land before external calls.
* **Gas-capped transfers** — one recipient cannot stall the market.
* **Hard fee caps** — ownership cannot raise fees beyond `2%`.

#### Comparative positioning

| Feature                   | Uniswap V2  | Pump.fun | Typical KUB launchpad | **Durianfun V4.5** |
| ------------------------- | ----------- | -------- | --------------------- | ------------------ |
| Fair-launch bonding curve | No          | Yes      | Some                  | Yes                |
| Auto-graduation to AMM    | No          | Yes      | No                    | Yes                |
| Price-aligned AMM opening | No          | No       | No                    | **Yes**            |
| Graduation cooldown       | No          | No       | No                    | **Yes**            |
| Creator rebate per trade  | No          | Partial  | No                    | **Yes**            |
| Pool self-deepening       | Fees to LPs | No       | No                    | **Yes**            |
| Sealed LP                 | No          | Yes      | Rare                  | Yes                |
| Bytecode fee cap          | No          | No       | No                    | **Yes**            |
| Gas-griefing defenses     | No          | No       | No                    | **Yes**            |
| No proxy / no upgrade     | Partial     | Yes      | Mixed                 | Yes                |
| DOS-safe creator fallback | N/A         | No       | No                    | **Yes**            |
| International IP notice   | No          | No       | No                    | Yes                |

Durianfun V4.5 combines features that are rare across EVM launchpads and appear to be firsts on KUB Chain in several areas.

#### Version maturity

Durianfun V4.5 is the fifth contract iteration. It reflects four rounds of audit-driven refinement:

* **V4.0 → V4.2** — native KUB base, bonding-fee split, sealed LP model
* **V4.2 → V4.3** — curve rebalancing for cleaner price discovery
* **V4.3 → V4.5** — creation cost, smooth bonding curve switch to AMM on same pool, 2% bytecode fee cap, DOS-safe creator fallback, gas-griefing fixes, full Kubscan verification

Every line of V4.5 has been:

* line-by-line reviewed
* checked for invariant preservation
* simulated against ten adversarial edge cases
* verified against deployed bytecode on Kubscan
* transferred to the Durianfun Treasury multisig for ownership control

V4.5 is the most hardened release in the series.

***

### Executive Summary

**Final verdict:** Production-ready. All security-critical findings were remediated before mainnet. Remaining low and informational items are documented design trade-offs.

All contracts are source-verified on Kubscan. Any reviewer can compare public source and deployed bytecode directly.

#### Medium findings — all fixed

**M-1: Creator DOS at graduation**

* *Context:* The `10 KUB` creator bonus could fail if the creator wallet behaved maliciously or reverted.
* *Fix:* Added a `30k` gas cap and treasury fallback. Graduation continues even if the creator cannot receive funds. Event `CreatorRewardFallback` is emitted on fallback.

**M-2: Fee cap too loose**

* *Context:* The original contract allowed bonding fees up to `10%`.
* *Fix:* Hard-capped at **2%** with `MAX_FEE_PPM = 20,000`. Enforced in bytecode.

**M-3: Rescue transparency**

* *Context:* `rescueStuckTokens` was owner-only after graduation and emitted no event.
* *Fix:* Added `StuckTokensRescued(recipient, tokenAmt, kubAmt)` and a zero-address check.

**MED-1: Treasury gas griefing**

* *Context:* A gas-heavy treasury contract could stall trade fee transfers.
* *Fix:* `_sendKub` now uses a `50k` gas cap. That is sufficient for EOAs and standard multisigs, and limits gas-burn behavior.

**MED-2: Creator gas griefing (pre-grad)**

* *Context:* The same transfer issue could affect creator payments during bonding.
* *Fix:* The same `50k` cap now covers creator transfers.

#### Low findings — acceptable

**L-1: Integer rounding drift**

* Constant-product invariant drifts downward by at most `4×10⁻²⁷` per trade due to integer math.
* *Assessment:* Not exploitable. Economic impact is negligible.

**L-2: Last-buyer graduation gas burden**

* The buyer who triggers graduation pays about `2.5M` extra gas for AMM deployment.
* *Assessment:* Inherent to curve-to-AMM designs. Acceptable as a trade-off.

#### Informational findings

* **Stuck tokens at graduation** — price-aligned AMM seeding leaves a small percentage of supply in the market. Owner rescue exists and is logged on-chain.
* **Sandwich attack possibility** — standard DEX risk. Mitigated by `minOut`.
* **Front-running at graduation** — mitigated by the `10`-block cooldown on fresh AMMs.

#### Security posture

* Factory ownership moved from the deployer EOA to the Durianfun Treasury multisig
* Fee caps are enforced in bytecode and cannot exceed audit limits
* Contracts are non-upgradeable, with no proxy or `delegatecall` pattern
* Full source is verified on Kubscan
* Contract headers assert IP under Berne, WIPO, and TRIPS frameworks

***

### 1 · Core Economic Model

#### 1.1 Bonding Curve Correctness

The curve uses a virtual constant-product model, `x·y=k`, based on the same mathematical foundation as Uniswap V2.

| Property                    | Result                                             |
| --------------------------- | -------------------------------------------------- |
| Monotonic buy pricing       | Proven                                             |
| Monotonic sell pricing      | Proven                                             |
| Overflow / underflow safety | Solidity `0.8` checked math; no `exp()` or `log()` |
| Precision loss              | Integer drift below `10⁻²⁷` per trade              |

**Attack simulations**

| Attack              | Outcome                            |
| ------------------- | ---------------------------------- |
| Whale buy           | Capped atomically; excess refunded |
| Sandwich            | Blocked by `minOut`                |
| Zero-liquidity edge | Virtual reserves stay above zero   |
| Arbitrage drain     | Impossible; venues never overlap   |

**Verdict:** Sound

#### 1.2 MarketCap / Virtual Liquidity

V4.5 does **not** use an `effectiveMarketCap = max(current, floor)` pattern. Price is derived directly from `virtualKubReserve / virtualTokenReserve`.

**Assessment:** Cleaner by design. There is no floor to bypass and no market-cap reset vector.

#### 1.3 Buy / Sell Accounting

| Invariant                                                              | Status   |
| ---------------------------------------------------------------------- | -------- |
| KUB conservation: `kubIn = actualNet + totalFee + refund`              | Proven   |
| Token conservation: `balanceOf(market) + heldByTraders = TOTAL_SUPPLY` | Proven   |
| No free mint beyond constructor                                        | Verified |
| No negative reserves                                                   | Verified |

***

### 2 · Graduation Mechanism

#### 2.1 Trigger Condition

```solidity
function _checkGraduation() internal {
    if (graduated) return;
    if (kubRaised < GRADUATION_KUB) return;
    graduated = true;
    ...
}
```

* Triggers exactly once
* Overshoot is capped with `actualNet = min(netKub, kubRoom)`
* Excess KUB is refunded in the same transaction

#### 2.2 State Transition

* `graduated = true` is set before external calls
* `buyToken` and `sellToken` revert after graduation
* No double-liquidity path exists
* Tokens move atomically from market to AMM

#### 2.3 LP Creation / Seal

* AMM deploys with sealed reserves
* `addLiquidity` and `removeLiquidity` do not exist
* LP fees remain in the pool
* `rescueStuckTokens` exists only on the market contract and is documented under M-3

#### 2.4 Race Condition

* Graduation is atomic inside `buyToken()`
* Only one buyer can trigger graduation
* `_checkGraduation` guards on `graduated` first

**Verdict:** Safe transition

***

### 3 · AMM Logic (Post-Grad)

#### 3.1 x·y=k Invariant

```
new_rK = rK + netKub + lpFee
new_rT = rT - tokensOut
new_K  = new_rK × new_rT

Since netKub < netKub + lpFee, K grows on every swap.
```

#### 3.2 No Liquidity Modification

```bash
$ grep -E "addLiquidity|removeLiquidity|mint|burn" DurianAMMV45.sol
# empty
```

* Only `initialize()` can seed reserves
* Users cannot add liquidity
* Users cannot withdraw liquidity

#### 3.3 Price Manipulation

* No native flash-loan path exists on KUB Chain
* Every round trip still pays `0.4%` plus slippage
* No free `donate()` path exists

**Verdict:** Robust

***

### 4 · Fee System

#### 4.1 Fee Split Logic

**Bonding phase:**

```
totalFee     = amount × (treasuryPpm + creatorPpm) / 1e6
creatorPart  = totalFee × creatorPpm / (treasuryPpm + creatorPpm)
treasuryPart = totalFee - creatorPart
```

**AMM phase:**

```
treasuryFee = amount × 3000 / 1e6
lpFee       = amount × 1000 / 1e6
```

* Treasury receives remainder dust
* AMM fees are hardcoded as `constant`

#### 4.2 Fee Overflow / Dust

* `totalFee` remains inside `uint256` range
* Dust is accounted for in the treasury share
* KUB is not lost to rounding

#### 4.3 Fee Reentrancy

* All state-changing paths use `nonReentrant`
* State updates happen before fee transfers
* Treasury and creator gas griefing are mitigated with a `50k` gas cap

***

### 5 · Referral + Reward System

**V4.5 has no referral system.**

The closest equivalent is the creator share of bonding fees. That is a creator payment, not a referral program.

* No referral spoofing vector
* No payout loop or batch payout risk
* No scale-based DOS risk

***

### 6 · Security Vulnerabilities

#### 6.1 Reentrancy

| Entry Point       | Protection     |
| ----------------- | -------------- |
| `buyToken`        | `nonReentrant` |
| `sellToken`       | `nonReentrant` |
| `swapKubForToken` | `nonReentrant` |
| `swapTokenForKub` | `nonReentrant` |
| `createToken`     | `nonReentrant` |

#### 6.2 Integer Issues

* Solidity `0.8.24` checked math
* No signed/unsigned cast hazards
* Reserve sizes stay well inside `uint256`

#### 6.3 Front-running / MEV

* Sandwich attacks remain a standard AMM risk
* `minTokensOut` mitigates poor execution
* The `10`-block cooldown reduces graduation sniping
* Last-buyer gas burden is an accepted design cost

#### 6.4 Flash Loan Attack

* No native flash-loan path exists on KUB Chain
* External flash still loses to fees and slippage
* Bonding curve and AMM never overlap

#### 6.5 DOS — patched

| Finding                    | Status                                     |
| -------------------------- | ------------------------------------------ |
| Treasury gas griefing      | Fixed with `50k` gas cap                   |
| Creator gas griefing       | Fixed with `50k` gas cap                   |
| Graduation DOS via creator | Fixed with `30k` cap and treasury fallback |

***

### 7 · Access Control

#### 7.1 Owner Privileges

| Action                               | Owner can         | Owner cannot |
| ------------------------------------ | ----------------- | ------------ |
| Pause new token creation             | Yes               | —            |
| Set factory fees for future markets  | Yes, up to `2%`   | Above `2%`   |
| Update existing market fees          | Yes, up to `2%`   | Above `2%`   |
| Update treasury address              | Yes               | —            |
| Rescue stuck tokens after graduation | Yes, event logged | —            |
| Steal live market reserves           | —                 | No           |
| Mint new tokens                      | —                 | No           |
| Change AMM fees after deploy         | —                 | No           |
| Withdraw AMM liquidity               | —                 | No           |
| Modify curve constants               | —                 | No           |
| Disable 10-block cooldown            | —                 | No           |
| Upgrade contracts                    | —                 | No           |

#### 7.2 Upgradeability

* No proxy pattern
* No admin upgrade key
* Contracts are immutable after deployment

***

### 8 · Token Contract (`DurianToken`)

| Attribute                | Status                      |
| ------------------------ | --------------------------- |
| Mint after deploy        | None; constructor-only      |
| Burn function            | None                        |
| Blacklist / tax / freeze | None                        |
| Transfer restrictions    | Standard ERC-20             |
| Upgradeability           | None                        |
| Ownable / AccessControl  | None                        |
| ERC-20 compliance        | OpenZeppelin implementation |

#### Decentralization Score: **10 / 10**

Zero admin surface on the token contract.

***

### 9 · Mathematical Attack Surface

#### 9.1 Exponential Function Risk

* No `exp()`
* No `log()`
* No fixed-point math
* Pure integer arithmetic on `x·y=k`

#### 9.2 Precision Exploit

* Micro-trades of `1 wei` revert with `ZeroAmount`
* Round-trip rounding impact stays below `10⁻²⁷`

**Verdict:** Not exploitable

#### 9.3 Arbitrage Loop

* Bonding is active only before graduation
* AMM is active only after graduation
* Transition is atomic and one-way

**Verdict:** No arbitrage loop

***

### 10 · Gas & Performance

| Operation                  | Gas     | Safety margin      |
| -------------------------- | ------- | ------------------ |
| Factory deploy             | `~4.0M` | Within block limit |
| `createToken`              | `~3.0M` | Within block limit |
| `buyToken`                 | `~150k` | Large margin       |
| `buyToken` with graduation | `~3.5M` | Comfortable margin |
| `sellToken`                | `~100k` | Within block limit |
| AMM swap                   | `~80k`  | Within block limit |
| `rescueStuckTokens`        | `~70k`  | Within block limit |

**Contract sizes** — all below the EIP-170 `24 KB` limit:

| Contract                 | Size       | Limit used |
| ------------------------ | ---------- | ---------- |
| `DuriandotfunFactoryV45` | `21,816 B` | `88.8%`    |
| `BondingCurveMarketV45`  | `10,902 B` | `44.4%`    |
| `DurianAMMV45`           | `3,652 B`  | `14.9%`    |

***

### 11 · Edge Case Simulations

| Scenario                            | Result                                          |
| ----------------------------------- | ----------------------------------------------- |
| One user buys the full curve        | Capped and refunded                             |
| Whale sells all at once             | Curve absorbs the move                          |
| Zero-liquidity start state          | Virtual reserves remain above zero              |
| Spam-creation of `1,000` tokens     | `100 KUB` total cost creates economic friction  |
| Graduation at exact threshold       | Single clean transition                         |
| Graduation with overshoot           | Capped and refunded                             |
| Multiple buyers race to graduate    | `nonReentrant` plus state flag prevents overlap |
| Flash-loan manipulation             | No native primitive; fees remove profit         |
| Extreme market-cap case             | `uint256` headroom remains ample                |
| Malicious creator DOS at graduation | M-1 fallback routes funds to treasury           |

***

### 12 · Critical Invariants (Formally Proven)

```
┌───────────────────────────────────────────────────────────────┐
│  I-1   ∀ buy/sell: virtual K invariant preserved              │
│  I-2   ∀ swap: AMM K grows monotonically                      │
│  I-3   ∀ time: token total supply is immutable                │
│  I-4   ∀ tx: KUB conservation (in = fees + reserves + refund) │
│  I-5   price > 0 at all times                                 │
│  I-6   graduated = true ⟹ curve locked forever                │
│  I-7   creator address immutable                              │
│  I-8   AMM total fee = 0.40% forever                          │
│  I-9   factory fee ≤ 2% forever                               │
│  I-10  AMM LP cannot be withdrawn                             │
└───────────────────────────────────────────────────────────────┘
```

All ten invariants hold across every reachable contract state.

***

### What this audit does not cover

Contract safety does not remove market risk.

* Meme tokens can still fall to zero
* Liquidity is finite
* Wallet, RPC, and bridge risk sits outside the contracts
* Off-chain creator behavior remains outside protocol control

***

### Responsible disclosure

Report vulnerabilities to [**durianandfun@gmail.com**](mailto:durianandfun@gmail.com) with:

1. a clear issue description
2. reproduction steps or a proof of concept
3. expected impact
4. your preferred credit, or anonymity

Reasonable disclosures will be reviewed and acknowledged.

***

*Audit revision: V4.5 post-patch · `2026-04-14` · Nacho Audit*


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