DRAM stablecoin

1 Executive Summary

This report presents the results of our engagement with DRAM to review their stable coin called Dram.

The review was conducted over two weeks, from August 14, 2023 to August 18, 2023, by Chingiz Mardanov. A total of 5 person-days were spent.

2 Scope

Our review focused on the commit hash 291600c50c295b3bc473c975d504bc5671d5fabe. The list of files in scope can be found in the Appendix. We have also conducted the review of fixes on the commit hash b70348e6998e35282212243ea639d174ced1ef2d.

After some time DRAM team identified that another coin with the same symbol was deployed and have made a decision to change the token symbol from DRM to DRAM. This update was done in commit 70fc1cd171acf0997f034e50e2ff53f44ef4e452 and does not modify anything else in the contracts that were a part of the audit.

2.1 Objectives

Together with the DRAM team, we identified the following priorities for our review:

  1. Correctness of the implementation, consistent with the intended functionality and without unintended edge cases.
  2. Identify known vulnerabilities particular to smart contract systems, as outlined in our Smart Contract Best Practices, and the Smart Contract Weakness Classification Registry.

3 System Overview

The code in question is a new stable coin that is going to be called Dram and will be primarily backed by the United Arab Emirates currency Dirham. As of right now the stable coin will be minted and initially distributed by the team.

Here are few notable functionalities present in the stable coin’s contract:

  • Freezing - malicious actor’s account can be frozen which will prevent Dram from being sent to or from them.
  • Minting and Burning - DRAM team can mint and burn the tokens as well as offer the ability to mint Dram to different operators up to a certain cap.
  • Pausing - Dram transfers can be paused completely.

4 Security Specification

This section describes, from a security perspective, the expected behavior of the system under audit. It is not a substitute for documentation. The purpose of this section is to identify specific security properties that were validated by the audit team.

4.1 Actors

The relevant actors are listed below with their respective abilities:

  • Role Manager - account that is responsible for adjusting the mint-caps (amount a specific wallet could mint) as well as granting new roles to other accounts.
  • Regulator - account that is capable of freezing and unfreezing the holder accounts. This will in turn either pause or unpause transfers of the tokens from and to the frozen account.
  • Supply Manager - account that is responsible for minting and burning the tokens that were either approved or transferred to it.
  • Admin - account that is capable of doing all of the above actions.

4.2 Trust Model

It’s worth noting that the Dram contracts are heavily centralized, and there are some basic assumptions about how the whole system will work that we should talk about.

The key thing to know about these contracts is that they can be upgraded. Depending on how they’re set up, the functions of these contracts might change whenever necessary.

Most of the important actions in the contract are controlled by specific roles that manage things like creating or destroying tokens, as well as freezing accounts. It’s crucial that these roles are well-protected and not vulnerable to any misuse by malicious parties.

As for the team at DRAM, they plan to put most roles, except for the REGULATORY_MANAGER_ROLE, behind a timelock contract. This means there’s a waiting period before those roles can take action. However, the REGULATORY_MANAGER_ROLE won’t have this delay since regulators might need to act quickly in emergencies. All these roles will be set up in a way where only the team’s multi-signature wallets can propose any changes to the contracts. It’s important to mention that while this setup is the plan, we can’t guarantee it will always be followed exactly, given the amount of human element involved.

5 Findings

Each issue has an assigned severity:

  • Minor issues are subjective in nature. They are typically suggestions around best practices or readability. Code maintainers should use their own judgment as to whether to address such issues.
  • Medium issues are objective in nature but are not security vulnerabilities. These should be addressed unless there is a clear reason not to.
  • Major issues are security vulnerabilities that may not be directly exploitable or may require certain conditions in order to be exploited. All major issues should be addressed.
  • Critical issues are directly exploitable security vulnerabilities that need to be fixed.

5.1 All Roles Are Set to the Same Account. Minor ✓ Fixed


All roles, including regulatory manager, are now set to different accounts. The modification can be found in commit b70348e6998e35282212243ea639d174ced1ef2d


From talking to the team we know that all roles will be held by different timelock contracts. In the code they all are initiated to the same admin address. That would mean that most roles would need to be transferred. Given that each transfer take 2 transactions and there are 3 roles to transfer that would equate to 6 transactions just to properly set up the contract on deployment. That also increments the time it would take and space for making errors.

It is also should be noted that the regulator role is not being initialized there at all.



// solhint-disable-next-line func-name-mixedcase
function __DramAccessControl_init_unchained(
    address admin
) internal onlyInitializing {
    _grantRole(ADMIN_ROLE, admin);
    _grantRole(ROLE_MANAGER_ROLE, admin);
    _grantRole(SUPPLY_MANAGER_ROLE, admin);


We suggest passing several addresses into the constructor and setting them to the correct addresses right away. Alternatively one can not set them at all and grant those roles later in order to avoid revoking the roles that admin should not have, such as SUPPLY_MANAGER_ROLE.

5.2 Setting MintCap to a Specific Value Is Prone to Front-Running. Minor


Acknowledged by the team with a comment: We will modify mintCaps using the increaseMintCap and decreaseMintCap functions.


Dram stable coin is using the approval-like model to set the minting caps of different operators, thus it is prone to the same front-run issues as the approval mechanism. When using the setMintCap function directly operator could front-run the transaction and completely spend the old cap and then spend the new one again after setting the transaction goes through.


function setMintCap(
    address operator,
    uint256 amount
) external onlyRoleOrAdmin(ROLE_MANAGER_ROLE) {
    _setMintCap(operator, amount);


Imagine the following scenario:

  1. Alice has a mint cap of 10.
  2. A transaction is sent to the mem-pool to set it to 5 (decrease the cap). The intent is that Alice should only be able to mint 5 tokens.
  3. Alice frontruns this transaction and mints 10 tokens.
  4. Once transaction 2 goes through Alice mints 5 more tokens.

In total Alice minted 15 tokens.


Avoid using setting the specific mint caps and rather use increase/decrease methods that are present in the code already.

5.3 Context.sol Is Not Required in the Present Use Case. Minor ✓ Fixed


Fixed in commit: b70348e6998e35282212243ea639d174ced1ef2d


ContextUpgradeable.sol contract that is used in the DramMintable contract can be regarded as a foundational contract, the methods of which are intended for overriding to facilitate the implementation of varying meta transaction logics.


abstract contract DramMintable is

In its isolated state, it brings no additional value but rather makes code evaluation more difficult.


In the case of DramMintable msg.sender can be used directly. In the case where meta-transactions are planned to be utilized, ContextUpgradeable.sol has to be overridden accordingly.

5.4 Admin Can Mint and Burn Tokens Which Is Not Immediately Evident From Code.


Burning and minting tokens functions both have the following modifier: onlyRole(SUPPLY_MANAGER_ROLE) which is different from onlyRoleOrAdmin used elsewhere. That implies that the Admin can not do minting or burning while in reality Admin can do that by just granting themselves a supply manager role first.



) external onlyRole(SUPPLY_MANAGER_ROLE) {


function burn(uint256 amount) external onlyRole(SUPPLY_MANAGER_ROLE) {

Appendix 1 - Files in Scope

This audit covered the following files:

File SHA-1 hash
contracts/Dram.sol c082e30f7ab6c4412119d8a0b1cf7a46464fd16a
contracts/access/DramAccessControl.sol eb6416f5c837f6b4a6b8e3e23552aafab5b506b0
contracts/access/DramFreezable.sol 7648a6545652adf32fb68a0ed09ea2df0f3c0a6a
contracts/access/IDramAccessControl.sol 882b9c60caa490b556ce451158bce31ef4e5321f
contracts/access/IDramFreezable.sol 7abccaca6c15103814651080a4f9b22fa2a7c45c
contracts/token/ERC20/extensions/DramMintable.sol 834270ea9c48dc6e82fddc05acdcc32ea5d93391
contracts/token/ERC20/extensions/IDramMintable.sol 70578fe21c5586fa222c6ed49635e5fa81d7427c

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