智能合约漏洞调研补充

漏洞分类

1. Incorrect Calculation/arithmetic issues ¹ Integer bugs

   1. arithmetic bugs

      Integer Overflow and Underflow Division by zero or modulo zero, 2）truncation bugs /multiply before divison/Imprecise arithmetic operations order 3）signedness bugs 目前精通整型溢出漏洞的工具:

   1. Osiris Integer bugs 论文
   2. ERC20 智能合约整数溢出系列漏洞披露 提到一个自动化工具可以高效挖掘高危整数溢出漏洞，检测出了文中很多漏洞

2. Use of Incorrect Operator/Typographical Error

   The unary + operator is deprecated in new solidity compiler versions.

3. Using Components with Known Vulnerabilities

   1. Outdated Compiler Version
   2. Compiler version not fixed / Floating Pragma

4. Unchecked Return Value / Handle errors in external calls ²

   Unchecked Call Return Value Uncheck low-level call

5. CWE-284: Improper Access Control ³

   1. Unprotected Ether Withdrawal

      unintentionally exposing initialization functions。such as Constructor 也可以说是初始化函数可见性问题 -- 见 SWC-105

   2. Unprotected SELFDESTRUCT Instruction/functionality / suicide ⁴

   3. Function Default Visibility -- Improper Adherence to Coding Standards⁵

   4. State Variable Default Visibility/Implicit visibility level(不明确指定可见性）⁶

   5. Owner 权限问题 避免 owner 权限过大

6. Improper Adherence to Coding Standards

   1. Shadowing State Variables [^write]

   2. Function Default Visibility

   3. Freezing ether⁷

      只有收钱，转账委托给其他合约，delegatecall，如果其他合约死了，就造成此问题

   4. Ether lost in transfer

      转向空地址

7. Incorrect Inheritance Order[^control_flow]

8. Use of Obsolete Function

   1. Use of Deprecated Solidity Functions
   2. Authorization through tx.origin[^authorization]⁸

9. CWE-841: Improper Enforcement of Behavioral Workflow 行为工作流的不恰当实施 [^improper_enforcement_workflow]⁹

   1. Reentrancy(a.k.a. recursive call attack) ¹⁰¹¹

      1. Reentrancy on a Single Function

      2. Cross-function Reentrancy

      3. Reentrancy Mutex 使用不当 when you have multiple contracts that need to cooperate.

         死锁

10. CWE-670: Always-Incorrect Control Flow Implementation[^control_flow]

    1. Assert Violation //存在某条控制流总是错误 1. 有 bug 或者 不该用 Assert

11. Insufficient Control Flow Management [^control_flow]

    1. Insufficient Gas Griefing[^gas]¹²

       subcall fail

       1. Require Gasleft 保证 subcall 完成
       2. Permit only trusted accounts to relay the transaction.

    2. Meta transactions Relay [^gas]¹³¹⁴¹⁵ 转发者不断提供较少 gas 使其失败，从而不断获取 ether 或者形成 Dos

12. Call to the unknown ¹⁶

    代码写错，未匹配到，默认调用 fallback 函数

13. CWE-829: Inclusion of Functionality from Untrusted Control Sphere¹⁷

    1. Delegatecall to Untrusted Callee

14. Mishandled Exceptions/Improper Check or Handling of Exceptional Conditions/Exception disorder ¹⁸

    1. DoS with Failed External Call¹⁹
    2. 未作限制的 DelegateCall

    参考: 以太坊 Solidity 合约 call 函数簇滥用导致的安全风险

15. Call 注入²⁰

16. Improper Following of Specification by Caller²¹

    1. Requirement Violation SWC-123

17. Race Condition/Concurrent Execution using Shared Resource with Improper Synchronization

    Front-runnig:²² 目前最常发生： The ERC20 token standard includes a function called 'approve'

    1. Displacement/顶替

    2. Insertion/Transaction Order Dependence 提前插队，倒卖

    3. Suppression/Block Stuffing attacks/Transaction Congestion Attack 拥挤堵塞²³

       The Anatomy of a Block Stuffing Attack

18. Weak Sources of Randomness from Chain Attributes/Use of Insufficiently Random Values/Entropy Illusion²⁴

    block.timestamp、blockhash ,   block.difficulty block Number 都是不安全的 1. Block values as a proxy for time/Timestamp dependence 2. Block Number Dependency

19. Improper Verification of Cryptographic Signature/Signature Replay Attacks[^authorization]

    1. Signature Malleability -- SWC-117

       ecrecover A signature should never be included into a signed message hash to check if previously messages have been processed by the contract.

    2. Missing Protection against Signature Replay Attacks -- SWC-121

       增加对重放攻击的保护，比如: 1.保存每次消息的 hash 2.Include the address of the contract that processes the message， 3. SWC-117

    3. Lack of Proper Signature Verification -- SWC-122

       sign messages off-chain. This can lead to vulnerabilities especially in scenarios where proxies can be used to relay transactions.

20. Write-what-where Condition

    Write to Arbitrary Storage Location²⁵

21. Use of Low-Level Functionality/Assembly instructions

    1. Arbitrary Jump with Function Type Variable

22. User Interface (UI) Misrepresentation of Critical Information

    Right-To-Left-Override control character (U+202E)

23. Irrelevant Code/Dead code

    1. Presence of unused variables
    2. Code With No Effects

24. Improper Locking

    Unexpected Ether balance/Forcibly Sending Ether to a Contract²⁶ In the worst case scenario this could lead to DOS conditions that might render the contract unusable.

25. Keeping secrets/Unencrypted Private Data On-Chain²⁷

    Access to Critical Private Variable via Public Method

26. Authentication Bypass by Capture-replay[^authorization]

    Hash Collisions With Multiple Variable Length Arguments

27. Improper Initialization

    Message call with hardcoded gas amount[^gas]

28. Gas

    1. Uncontrolled Resource Consumption

       DoS With Block Gas Limit²⁸

       1. Gas Limit DoS on a Contract via Unbounded Operations/Loop over an array of unknown size

          lock Ether

       2. Gas Limit DoS on the Network via Block Stuffing/Block Stuffing attacks/Transaction congestion Attack

       它不只可以用来消耗 Gas， 还可以通过 GasToken 来倒成钱

    2. GasLess Send

    参考：Silent But Vulnerable: Ethereum Gas Security Concerns

29. Dos²⁹

    1. DoS With Block Gas Limit

       1. DoS with Failed External Call/External calls without gas stipends³⁰
       2. Looping through externally manipulated mappings or arrays/通过外部操纵映射或数组（Array）循环

    2. Owner operations 所有者操作

    3. Progressing state based on external calls 基于外部调用的进展状态³¹

       见 Solidity Security: Comprehensive list of known attack vectors and common anti-patterns 中文翻译

    4. DoS with (Unexpected) revert ³²

       恶意退款的 fallback 函数

30. Signature collisions: two different functions may have the same signature

31. 假充值问题 专门做它的: 1.EVulHunter: Detecting Fake Transfer Vulnerabilitiesfor EOSIO’s Smart Contracts at Webassembly level 2. 知道创宇 404/慢雾团队

版本更新已解决

1. Uninitialized Storage Pointer~~~ compiler version 0.5.0 and higher 已解决

2. Incorrect Constructor Name -- SWC-118 Solidity version 0.4.22 引入了 constructor 关键字

参照

SWC Registry Classification of smart contract vulnerabilities Known Attacks Silent But Vulnerable: Ethereum Gas Security Concerns Solidity Security: Comprehensive list of known attack vectors and common anti-patterns ethereum wiki 智能合约的常见漏洞 以太坊智能合约安全入门了解一下（上） 区块链智能合约安全审计白皮书（2018 年）解读 以太坊 Solidity 合约 call 函数簇滥用导致的安全风险

想法总结

以太坊 Solidity 合约 call 函数簇滥用导致的安全风险 call 安全漏洞

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1. 算数溢出等数学方面的问题↩︎

2. 专门检测返回值↩︎

3. 专门检测权限控制↩︎

4. ：专门检测可以合约损毁自杀的↩︎

5. 属于权限控制↩︎

6. 属于权限控制↩︎

7. 检测不当调用，从而检测调用引起的异常等其他危险↩︎

8. 专门检测权限控制↩︎

9. 顺序相关 [^gas]：与 Gas 相关的↩︎

10. 与 fallback 函数相关的↩︎

11. 检测从别的域包含/执行(外部)代码的类型↩︎

12. 代理转发相关↩︎

13. 代理转发相关↩︎

14. 漏洞↩︎

15. ether 相关，1. 攻击获得 2. 丢失 3. 锁定 lock↩︎

16. 与 fallback 函数相关的↩︎

17. 检测不当调用，从而检测调用引起的异常等其他危险↩︎

18. 检测不当调用，从而检测调用引起的异常等其他危险↩︎

19. 漏洞↩︎

20. 检测不当调用，从而检测调用引起的异常等其他危险↩︎

21. 检测不当调用，从而检测调用引起的异常等其他危险↩︎

22. 顺序相关 [^gas]：与 Gas 相关的↩︎

23. 漏洞↩︎

24. 检测从别的域包含/执行(外部)代码的类型↩︎

25. 专门检测权限控制↩︎

26. 漏洞↩︎

27. 属于权限控制↩︎

28. 漏洞↩︎

29. 漏洞↩︎

30. 调用外部合约↩︎

31. 调用外部合约↩︎

32. 与 fallback 函数相关的↩︎