Selfdestruct Removal Analysis 3

This follows from the first and second selfdestruct removal analysis reports.

As explained in previous reports, there are two use-cases which will be broken if SELFDESTRUCT is replaced with SENDALL using EIP-4758:

• upgradable contracts created using CREATE2 which can be selfdestructed and a new contract deployed at the same address.
• ephemeral contract creators: contracts which were intended to be created and selfdestructed in the same transaction now remain deployed after executing SENDALL.

This document gives an overview of contracts on mainnet that are confirmed/probable upgradable and creators of ephemeral contracts. A contract is considered upgradable if it has been created using CREATE2 and has a reachable SELFDESTRUCT opcode in its bytecode.

When determining whether a contract has a reachable SELFDESTRUCT, we want to detect solidity metadata appended to the contract bytecode. This can contain arbitrary bytes so any SELFDESTRUCT opcode in it must not be considered. The heuristic used here is to consider the metadata to be any bytes past two adjacent 0x00 and 0xa2 opcodes.

The dataset used can be reproduced using these instructions.

Note: a contract is considered recently-active if it has been the sender/receiver of an internal call or transaction since block 15900000.

Findings Summary

Potentially-Upgradable Addresses

Total of 2058022 existing selfdestructable contracts were created by 404 creators with only CREATE2 in their bytecode. 176110 were created by 304 creators with both CREATE2 and CREATE. 144735 have non-zero eth balances and 39204 were recently-active.

Creators by Balance

42 addresses with non-zero Eth balances. Top 10:

Creators by Recent Activity

57 addresses with recent activity. Top 10:

Previously-reinited Selfdestructable contract addresses with create2-containing creators

1992 selfdestructable contracts deployed by 89 creators.

Top Creators by Recent Activity

14 contracts were recently active. Top 10:

Top Create2-containing Creators by Balance

9 contracts had non-zero balances:

Top Created Contracts by Balance

35 contracts had non-zero balances. Top 10:

Top Created Contracts By Recent Activity

45 contracts with create2-containing creators were recently-active. Top 10:

Ephemeral Contract Creators

Total of 9811 alive contracts that have previously created ephemeral contracts. 429 have non-zero Eth balances. 60 were recently active.

Top Contracts by Recent Activity

Top Contracts By Balance

Top Contracts Ranked by Number of Created Ephemeral Contracts

Etherscan gave no indication what these addresses were/are used for.

Interpretation

There are many selfdestructable contracts deployed on mainnet that could break with a blanket selfdestruct removal as proposed in EIP-4758. EIP-6046 is an alternative approach which provides backwards-compatible behavior for many on-chain contracts that would be broken by 4758. However, it has edge-cases that need consideration/investigation.

Looking at recent on-chain usage and Eth balance are good ways to prioritize potentially-affected contracts for manual analysis. However, we have to consider consider cases where disabling a low-value/rarely-used upgradeable contract could lock value in other contracts that depend on it.

Further automated analysis is needed to identify how potentially-affected contracts are related to other on-chain contracts: looking at history of interactions and doing static analysis to identify likely-addresses in code/storage, identify cases where these could be the address argument to a CALL* might provide useful insights.