pragma solidity ^0.4.24;


 
contract ERC20Basic {
  function totalSupply() public view returns (uint256);
  function balanceOf(address who) public view returns (uint256);
  function transfer(address to, uint256 value) public returns (bool);
  event Transfer(address indexed from, address indexed to, uint256 value);
}





 
contract ERC20 is ERC20Basic {
  function allowance(address owner, address spender) public view returns (uint256);
  function transferFrom(address from, address to, uint256 value) public returns (bool);
  function approve(address spender, uint256 value) public returns (bool);
  event Approval(address indexed owner, address indexed spender, uint256 value);
}



 
contract BasicToken is ERC20Basic {
  using SafeMath for uint256;

  mapping(address => uint256) balances;

  uint256 totalSupply_;

   
  function totalSupply() public view returns (uint256) {
    return totalSupply_;
  }

   
  function transfer(address _to, uint256 _value) public returns (bool) {
    require(_to != address(0));
    require(_value <= balances[msg.sender]);

    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    emit Transfer(msg.sender, _to, _value);
    return true;
  }

   
  function balanceOf(address _owner) public view returns (uint256) {
    return balances[_owner];
  }

}




 
contract Ownable {
  address public owner;


  event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);


   
  function Ownable() public {
    owner = msg.sender;
  }

   
  modifier onlyOwner() {
    require(msg.sender == owner);
    _;
  }

   
  function transferOwnership(address newOwner) public onlyOwner {
    require(newOwner != address(0));
    emit OwnershipTransferred(owner, newOwner);
    owner = newOwner;
  }

}














 
contract StandardToken is ERC20, BasicToken {

  mapping (address => mapping (address => uint256)) internal allowed;


   
  function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
    require(_to != address(0));
    require(_value <= balances[_from]);
    require(_value <= allowed[_from][msg.sender]);

    balances[_from] = balances[_from].sub(_value);
    balances[_to] = balances[_to].add(_value);
    allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
    emit Transfer(_from, _to, _value);
    return true;
  }

   
  function approve(address _spender, uint256 _value) public returns (bool) {
    allowed[msg.sender][_spender] = _value;
    emit Approval(msg.sender, _spender, _value);
    return true;
  }

   
  function allowance(address _owner, address _spender) public view returns (uint256) {
    return allowed[_owner][_spender];
  }

   
  function increaseApproval(address _spender, uint _addedValue) public returns (bool) {
    allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
    emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }

   
  function decreaseApproval(address _spender, uint _subtractedValue) public returns (bool) {
    uint oldValue = allowed[msg.sender][_spender];
    if (_subtractedValue > oldValue) {
      allowed[msg.sender][_spender] = 0;
    } else {
      allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
    }
    emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }

}




 
contract MintableToken is StandardToken, Ownable {
  event Mint(address indexed to, uint256 amount);
  event MintFinished();

  bool public mintingFinished = false;


  modifier canMint() {
    require(!mintingFinished);
    _;
  }

   
  function mint(address _to, uint256 _amount) onlyOwner canMint public returns (bool) {
    totalSupply_ = totalSupply_.add(_amount);
    balances[_to] = balances[_to].add(_amount);
    emit Mint(_to, _amount);
    emit Transfer(address(0), _to, _amount);
    return true;
  }

   
  function finishMinting() onlyOwner canMint public returns (bool) {
    mintingFinished = true;
    emit MintFinished();
    return true;
  }
}



 
contract CappedToken is MintableToken {

  uint256 public cap;

  function CappedToken(uint256 _cap) public {
    require(_cap > 0);
    cap = _cap;
  }

   
  function mint(address _to, uint256 _amount) onlyOwner canMint public returns (bool) {
    require(totalSupply_.add(_amount) <= cap);

    return super.mint(_to, _amount);
  }

}


 
contract BurnableToken is BasicToken {

  event Burn(address indexed burner, uint256 value);

   
  function burn(uint256 _value) public {
    _burn(msg.sender, _value);
  }

  function _burn(address _who, uint256 _value) internal {
    require(_value <= balances[_who]);
     
     

    balances[_who] = balances[_who].sub(_value);
    totalSupply_ = totalSupply_.sub(_value);
    emit Burn(_who, _value);
    emit Transfer(_who, address(0), _value);
  }
}


 
 
contract CareerChainToken is CappedToken(145249999000000000000000000), BurnableToken  {
    string public name = "CareerChain Token";
    string public symbol = "CCH";
    uint8 public decimals = 18;

     
    function burn(uint256 _value) public onlyOwner {
      _burn(msg.sender, _value);

    }

}




 
library SafeMath {

   
  function mul(uint256 a, uint256 b) internal pure returns (uint256 c) {
    if (a == 0) {
      return 0;
    }
    c = a * b;
    assert(c / a == b);
    return c;
  }

   
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
     
     
     
    return a / b;
  }

   
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a);
    return a - b;
  }

   
  function add(uint256 a, uint256 b) internal pure returns (uint256 c) {
    c = a + b;
    assert(c >= a);
    return c;
  }
}



 
contract Crowdsale {
  using SafeMath for uint256;

   
  ERC20 public token;

   
  address public wallet;

   
  uint256 public rate;

   
  uint256 public weiRaised;

   
  event TokenPurchase(address indexed purchaser, address indexed beneficiary, uint256 value, uint256 amount);

   
  function Crowdsale(uint256 _rate, address _wallet, ERC20 _token) public {
    require(_rate > 0);
    require(_wallet != address(0));
    require(_token != address(0));

    rate = _rate;
    wallet = _wallet;
    token = _token;
  }

   
   
   

   
  function () external payable {
    buyTokens(msg.sender);
  }

   
  function buyTokens(address _beneficiary) public payable {

    uint256 weiAmount = msg.value;
    _preValidatePurchase(_beneficiary, weiAmount);

     
    uint256 tokens = _getTokenAmount(weiAmount);

     
    weiRaised = weiRaised.add(weiAmount);

    _processPurchase(_beneficiary, tokens);
    emit TokenPurchase(
      msg.sender,
      _beneficiary,
      weiAmount,
      tokens
    );

    _updatePurchasingState(_beneficiary, weiAmount);

    _forwardFunds();
    _postValidatePurchase(_beneficiary, weiAmount);
  }

   
   
   

   
  function _preValidatePurchase(address _beneficiary, uint256 _weiAmount) internal {
    require(_beneficiary != address(0));
    require(_weiAmount != 0);
  }

   
  function _postValidatePurchase(address _beneficiary, uint256 _weiAmount) internal {
     
  }

   
  function _deliverTokens(address _beneficiary, uint256 _tokenAmount) internal {
    token.transfer(_beneficiary, _tokenAmount);
  }

   
  function _processPurchase(address _beneficiary, uint256 _tokenAmount) internal {
    _deliverTokens(_beneficiary, _tokenAmount);
  }

   
  function _updatePurchasingState(address _beneficiary, uint256 _weiAmount) internal {
     
  }

   
  function _getTokenAmount(uint256 _weiAmount) internal view returns (uint256) {
    return _weiAmount.mul(rate);
  }

   
  function _forwardFunds() internal {
    wallet.transfer(msg.value);
  }
}




 
contract WhitelistedCrowdsale is Crowdsale, Ownable {

  mapping(address => bool) public whitelist;

   
  modifier isWhitelisted(address _beneficiary) {
    require(whitelist[_beneficiary]);
    _;
  }

   
  function addToWhitelist(address _beneficiary) external onlyOwner {
    whitelist[_beneficiary] = true;
  }

   
  function addManyToWhitelist(address[] _beneficiaries) external onlyOwner {
    for (uint256 i = 0; i < _beneficiaries.length; i++) {
      whitelist[_beneficiaries[i]] = true;
    }
  }

   
  function removeFromWhitelist(address _beneficiary) external onlyOwner {
    whitelist[_beneficiary] = false;
  }

   
  function _preValidatePurchase(address _beneficiary, uint256 _weiAmount) internal isWhitelisted(_beneficiary) {
    super._preValidatePurchase(_beneficiary, _weiAmount);
  }

}







 
contract TimedCrowdsale is Crowdsale {
  using SafeMath for uint256;

  uint256 public openingTime;
  uint256 public closingTime;

   
  modifier onlyWhileOpen {
     
    require(block.timestamp >= openingTime && block.timestamp <= closingTime);
    _;
  }

   
  function TimedCrowdsale(uint256 _openingTime, uint256 _closingTime) public {
     
    require(_openingTime >= block.timestamp);
    require(_closingTime >= _openingTime);

    openingTime = _openingTime;
    closingTime = _closingTime;
  }

   
  function hasClosed() public view returns (bool) {
     
    return block.timestamp > closingTime;
  }

   
  function _preValidatePurchase(address _beneficiary, uint256 _weiAmount) internal onlyWhileOpen {
    super._preValidatePurchase(_beneficiary, _weiAmount);
  }

}


 
contract CareerChainPrivateSale is TimedCrowdsale, WhitelistedCrowdsale  {
    using SafeMath for uint256;

     
    uint256 public tokensStillInLockup;

     
    uint256[6] public lockupEndTime;

     
    mapping(address => uint256) public balances;

     
    mapping(address => uint256) public released;

     
    uint256 public firstVestedLockUpAmount;
    uint256 public stagedVestedLockUpAmounts;

     
     
    function CareerChainPrivateSale
        (
            uint256 _openingTime,
            uint256 _closingTime,
            uint256 _rate,
            address _wallet,
            uint256[6] _lockupEndTime,
            uint256 _firstVestedLockUpAmount,
            uint256 _stagedVestedLockUpAmounts,
            CareerChainToken _token
        )
        public
        Crowdsale(_rate, _wallet, _token)
        TimedCrowdsale(_openingTime, _closingTime)
        {
             
            require(_lockupEndTime[0] >= block.timestamp);
            require(_lockupEndTime[1] >= _lockupEndTime[0]);
            require(_lockupEndTime[2] >= _lockupEndTime[1]);
            require(_lockupEndTime[3] >= _lockupEndTime[2]);
            require(_lockupEndTime[4] >= _lockupEndTime[3]);
            require(_lockupEndTime[5] >= _lockupEndTime[4]);

            lockupEndTime = _lockupEndTime;

            firstVestedLockUpAmount = _firstVestedLockUpAmount;
            stagedVestedLockUpAmounts = _stagedVestedLockUpAmounts;
        }


     
     
     
    function _processPurchase(address _beneficiary, uint256 _tokenAmount) internal {

        uint256 newTokensSold = tokensStillInLockup.add(_tokenAmount);
        require(newTokensSold <= token.balanceOf(address(this)));
        tokensStillInLockup = newTokensSold;

         
        balances[_beneficiary] = balances[_beneficiary].add(_tokenAmount);

    }

     
     
    function TransferUnsoldTokensBackToTokenContract(address _beneficiary) public onlyOwner {

        require(hasClosed());
        uint256 unSoldTokens = token.balanceOf(address(this)).sub(tokensStillInLockup);

        token.transfer(_beneficiary, unSoldTokens);
    }

     
     
     
    function IssueTokensToInvestors(address _beneficiary, uint256 _amount) public onlyOwner onlyWhileOpen{

        require(_beneficiary != address(0));
        _processPurchase(_beneficiary, _amount);
    }

     
    function _changeRate(uint256 _rate) public onlyOwner {
        require(_rate > 0);
        rate = _rate;
    }

     
    function releasableAmount() private view returns (uint256) {
      return vestedAmount().sub(released[msg.sender]);
    }

     
    function vestedAmount() private view returns (uint256) {
      uint256 lockupStage = 0;
      uint256 releasable = 0;

       
      uint256 i=0;
      while (i < lockupEndTime.length && lockupEndTime[i]<=now)
      {
        lockupStage = lockupStage.add(1);
        i = i.add(1);
      }

       
      if(lockupStage>0)
      {
         
        releasable = (lockupStage.sub(1).mul(stagedVestedLockUpAmounts)).add(firstVestedLockUpAmount);
      }
      return releasable;
    }

     
    function withdrawTokens() public {
      uint256 tobeReleased = 0;
      uint256 unreleased = releasableAmount();

       
      if(balances[msg.sender] >= unreleased && lockupEndTime[lockupEndTime.length-1] > now)
      {
        tobeReleased = unreleased;
      }
      else
      {
        tobeReleased = balances[msg.sender];
      }

       
      require(tobeReleased > 0);

      balances[msg.sender] = balances[msg.sender].sub(tobeReleased);
      tokensStillInLockup = tokensStillInLockup.sub(tobeReleased);
      released[msg.sender] = released[msg.sender].add(tobeReleased);

      _deliverTokens(msg.sender, tobeReleased);

    }

}

Detected vulnerabilities:
TimedCrowdsale: Timestamp Dependency
CareerChainPrivateSale: Timestamp Dependency