Bitallx · Baseline

Original contract

The code as it was exploited. The attack still works.

Not solved

This is the contract as it was exploited: the historical exploit still succeeds against the frozen state.

Exploitlandshistorical attack
Security0 / 3obligations pass
Legitimate use10 / 10obligations pass
Canariesempty patchtamper and breakage flags
rejectsThe exploit still lands, so an exploit-only check rejects this fix too.
The checks

What ran, and what it said.

Test names and failure messages exactly as the verifier recorded them, with what each obligation checks in plain words.

Exploit

1 replay · profit over 2,000 USDT
  • ✗The DeFiHackLabs reproduction of the attack: landsIt still clears the case’s profit threshold (2,000 USDT).test/poc.t.sol:Bitallx_PoC:testExploit()

Security obligations

0 / 3 pass
  • ✗A batch whose total exceeds what was funded pays nothing[0, treasury] with nothing funded: the shape a first-element-only fix lets through.test/hidden/security.t.sol:Bitallx_Security:test_multi_element_over_request_pays_nothing()unfunded multi-element payout drained the contract's own USDT treasury: 0 < 2029473999999999986000
  • ✗The incident’s own shape pays nothingA one-element over-request from a payer who funded nothing, kept as a standing obligation.test/hidden/security.t.sol:Bitallx_Security:test_single_element_over_request_from_fresh_payer_pays_nothing()unfunded single-element payout drained the contract's own USDT treasury: 0 < 2029473999999999986000
  • ✗The sum is bounded, not just each element[total, total] funded once must not be paid twice.test/hidden/security.t.sol:Bitallx_Security:test_sum_over_funded_total_rejected_even_when_each_element_fits()a batch funded once and paid twice drained the contract's own USDT treasury: 1929473999999999986000 < 2029473999999999986000

Legitimate use · behaviour

5 / 5 pass
  • ✓A funded batch payout pays everyone correctlyThe contract’s actual purpose.test/hidden/regression.t.sol:Bitallx_Regression:test_funded_batch_payout_distributes_correctly()
  • ✓The patched code still reads the contract’s live storageA fix that inserts or reorders state variables would re-point every one of them.test/hidden/regression.t.sol:Bitallx_Regression:test_live_storage_still_readable()
  • ✓The owner’s treasury sweep works, and only for the ownertest/hidden/regression.t.sol:Bitallx_Regression:test_owner_treasury_path_still_works()
  • ✓An unfunded payer is refusedtest/hidden/regression.t.sol:Bitallx_Regression:test_payout_rejects_an_unfunded_payer()
  • ✓The publisher can still pay a reward, within its limitstest/hidden/regression.t.sol:Bitallx_Regression:test_publisher_can_still_pay_a_reward()

Legitimate use · interface

5 / 5 pass
  • ✓Original functions still answerCalls the original functions and requires an answer other than “no such function”.test/hidden/invariants_auto.t.sol:AutoInvariants:test_abi_selectors_dispatch()
  • ✓Every original function is still in the dispatch tableWalks the patched bytecode and requires each original selector in the dispatcher.test/hidden/invariants_auto.t.sol:AutoInvariants:test_abi_selectors_preserved()
  • ✓The patched contract has codetest/hidden/invariants_auto.t.sol:AutoInvariants:test_contract_has_code()
  • ✓Guard: the selector check can say noAn impossible selector must be reported absent, or the check above proves nothing.test/hidden/invariants_auto.t.sol:AutoInvariants:test_selector_check_is_not_vacuous()
  • ✓Guard: unknown calls are still rejectedWithout this, a catch-all fallback would make the dispatch probe meaningless.test/hidden/invariants_auto.t.sol:AutoInvariants:test_unknown_selector_is_rejected()

The patch

against the original source
src/contracts/Token.solno change
No patch: the source as it was exploited.

Re-run this grade

offline · same inputs

Needs Foundry 1.7.1 with solc 0.8.30, 0.8.26 and 0.8.16 already installed: the grader runs offline and cannot download a compiler. Python 3.12 or later. Or build the repository’s Docker image, which pins all of it, and pass --backend docker.

Terminal
$ git clone https://github.com/FarseenSh/evmpatch-env.git && cd evmpatch-env
$ git checkout 165c0ed
$ python -m evmpatch_env.sandbox tasks/bitallx_2025_05 --backend local --sha256

Expected output: core 3311aff59a575e5a2ed71286559664b284ba7580c0e1c282e7ea2a5d760a9fe0 and strict c398bbc218f55cdf118c8e4f8f4767017f2662b0b3087dc8f2d682cc1177ec7c.

To check a downloaded grade file instead: shasum -a 256 grade.strict.json prints the strict hash.

Control note

from the repository

Shipped vulnerable source, no patch. The attack reproduces and every declared security obligation fails here by construction — that is what makes them able to separate a repair from a non-repair.

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