The tx.origin global variable holds the address of the account from where a transaction originates.

If a smart contract, S1, receives a transaction from an account, A1, and then S1 calls another smart contract, S2, then inside S2, tx.origin contains the address of account, A1, used for calling S1. If the intent of tx.origin is to verify authorization of A1, then this authorization is bypassed.

Now, if an attacker can trick a user into sending a transaction into a malicious contract that them invokes the vulnerable contract where the user is authorized via tx.origin, then tx.origin will hold the address of the user account that initiated the transaction and authorization will be bypassed.

Example 1: The following code requires the owner of the contract (previously set in the constructor) to be the same as tx.origin before transferring funds to a provided address.

If an attacker is able to trick the owner of the contract into sending a transaction to a malicious contract which immediately calls the sendTo function in the vulnerable contract, then the condition within the require statement will be true and funds will be transferred to whatever address the attacker contract specified when calling sendTo.

function sendTo(address receiver, uint amount) public {
    require(tx.origin == owner);
    receiver.transfer(amount);
}

Customer-managed keys are not used to encrypt data at rest.

By default, AWS uses AWS-managed keys to encrypt data at rest if encryption is enabled. Customer-managed keys enable organizations to use cryptographic keys of their choice to encrypt data. This gives organizations better control over and logging of encryption processes.

As such, customer-managed keys are often part of the solution to address requirements that include but are not limited to:
- Audit logs for sensitive data access
- Data residency
- Replacing, disabling, or destroying keys

Note that keys with the format aws/service-name are reserved for AWS-managed keys.

Loose access configurations can expose systems and broaden an organization's attack surface. Services open to interaction with the public are typically subjected to near-continuous scanning and probing by malicious entities.

This is especially problematic when a zero-day exploit for an exposed service is discovered and published, such as Heartbleed. Attackers can actively pursue and search for unpatched and exposed systems to exploit.

Loose access configurations unnecessarily expose systems and broaden an organization's attack surface. Services open to interaction with the public are typically subjected to near continuous scanning and probing by malicious entities.

This is especially problematic when a zero-day exploit for an exposed service is discovered and published (e.g Heartbleed). Attackers can actively pursue and search for unpatched and exposed systems to exploit.

Example 1: The following Ansible task defines an AWS Security Group that opens to the world (0.0.0.0/0) the TCP port 22, where an SSH server typically responds to incoming connection requests.

- name: Task to open SSH port
  amazon.aws.ec2_group:
    name: demo_security_group
    description: Open the ssh port to the world
    state: present
    vpc_id: 123456
    region: us-west-1
    rules:
    - proto: tcp
        ports: 22
        cidr_ip: 0.0.0.0/0

Uncontrolled access to critical or sensitive resources can significantly impact an organization in various ways, including disclosure of or tampering with critical data.

Loose access configurations can expose systems and broaden an organization's attack surface. Services open to interaction with the public are typically subjected to near-continuous scanning and probing by malicious entities.

This is especially problematic when a zero-day exploit for an exposed service is discovered and published, such as Heartbleed. Attackers can actively pursue and search for unpatched and exposed systems to exploit.

IAM policies allowing unrestricted access to resources place an organization at risk. Poorly structured policies undermine the ability of an organization to control and manage changes to resources.