Severity scoring for Amazon Macie findings
When Amazon Macie generates a policy or sensitive data finding, it automatically assigns a severity to the finding. A finding's severity reflects the principal characteristics of the finding and can help you assess and prioritize your findings. A finding's severity doesn't imply or otherwise indicate the criticality or importance that an affected resource might have for your organization.
For policy findings, severity is based on the nature of a potential issue with the security or privacy of an Amazon Simple Storage Service (Amazon S3) general purpose bucket. For sensitive data findings, severity is based on the nature and number of occurrences of sensitive data that Macie found in an S3 object.
In Macie, a finding's severity is represented in two ways.
- Severity level
-
This is a qualitative representation of severity. Severity levels range from Low, for least severe, to High, for most severe.
Severity levels appear directly on the Amazon Macie console. They're also available in JSON representations of findings on the Macie console, from the Amazon Macie API, and in sensitive data discovery results that correlate to sensitive data findings. Severity levels are also included in finding events that Macie publishes to Amazon EventBridge and findings that Macie publishes to AWS Security Hub.
- Severity score
-
This is a numerical representation of severity. Severity scores range from 1 through 3 and map directly to severity levels:
Severity score Severity level 1 Low 2 Medium 3 High Severity scores don't appear directly on the Amazon Macie console. However, they're available in JSON representations of findings on the Macie console, from the Amazon Macie API, and in sensitive data discovery results that correlate to sensitive data findings. Severity scores are also included in finding events that Macie publishes to Amazon EventBridge. They aren't included in findings that Macie publishes to AWS Security Hub.
The topics in this section indicate how Macie determines the severity of policy findings and sensitive data findings.
Severity scoring for policy findings
The severity of a policy finding is based on the nature of a potential issue with the security or privacy of an S3 general purpose bucket. The following table lists the severity levels that Macie assigns to each type of policy finding. For a description of each type, see Types of findings.
| Finding type | Severity level |
|---|---|
| Policy:IAMUser/S3BlockPublicAccessDisabled | High |
|
Policy:IAMUser/S3BucketEncryptionDisabled |
Low |
| Policy:IAMUser/S3BucketPublic | High |
| Policy:IAMUser/S3BucketReplicatedExternally | High |
| Policy:IAMUser/S3BucketSharedExternally | High |
| Policy:IAMUser/S3BucketSharedWithCloudFront | Medium |
The severity of a policy finding doesn't change based on the number of occurrences of the finding.
Severity scoring for sensitive data findings
The severity of a sensitive data finding is based on the nature and number of occurrences of sensitive data that Macie found in an S3 object. The following topics indicate how Macie determines the severity of each type of sensitive data finding:
For detailed information about the types of sensitive data that Macie can detect and report in sensitive data findings, see Using managed data identifiers and Building custom data identifiers.
SensitiveData:S3Object/Credentials
A SensitiveData:S3Object/Credentials finding indicates that an S3 object contains sensitive credentials data. For this type of finding, Macie determines severity based on the type and number of occurrences of the credentials data that Macie found in the object.
The following table indicates the severity levels that Macie assigns to findings that report occurrences of credentials data in an S3 object.
| Sensitive data type | 1 occurrence | 2–99 occurrences | 100 or more occurrences |
|---|---|---|---|
| AWS secret access key | High | High | High |
| Google Cloud API key | High | High | High |
| HTTP Basic Authorization header | High | High | High |
| JSON Web Token (JWT) | High | High | High |
| OpenSSH private key | High | High | High |
| PGP private key | High | High | High |
| Public-Key Cryptography Standard (PKCS) private key | High | High | High |
| PuTTY private key | High | High | High |
| Stripe API key | High | High | High |
SensitiveData:S3Object/CustomIdentifier
A SensitiveData:S3Object/CustomIdentifier finding indicates that an S3 object contains text that matches the detection criteria of one or more custom data identifiers. The object might contain more than one type of sensitive data.
By default, Macie assigns the Medium severity level to this type of finding—if the S3 object contains at least one occurrence of text that matches the detection criteria of at least one custom data identifier, Macie automatically assigns the Medium severity level to the finding. The severity of the finding doesn't change based on the number of occurrences of text that match a custom data identifier's criteria.
However, the severity of this type of finding can vary if you defined custom severity settings for a custom data identifier that produced the finding. If this is the case, Macie determines severity as follows:
-
If the S3 object contains text that matches the detection criteria of only one custom data identifier, Macie determines the finding's severity based on the severity settings for that identifier.
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If the S3 object contains text that matches the detection criteria of more than one custom data identifier, Macie determines the finding's severity by evaluating the severity settings for each custom data identifier, determining which of those settings produces the highest severity, and then assigning that highest severity to the finding.
To review the severity settings for a custom data identifier, choose Custom data identifiers in the navigation pane on the Amazon Macie console. Then choose the name of the custom data identifier. The Severity section shows the settings. For more information, see Defining finding severity settings for custom data identifiers.
SensitiveData:S3Object/Financial
A SensitiveData:S3Object/Financial finding indicates that an S3 object contains sensitive financial information. For this type of finding, Macie determines severity based on the type and number of occurrences of the financial information that Macie found in the object.
The following table indicates the severity levels that Macie assigns to findings that report occurrences of financial information in an S3 object.
| Sensitive data type | 1 occurrence | 2–99 occurrences | 100 or more occurrences |
|---|---|---|---|
|
Bank account number 1 |
High | High | High |
|
Credit card expiration date |
Low | Medium | High |
|
Credit card magnetic stripe data |
High | High | High |
|
Credit card number 2 |
High | High | High |
|
Credit card verification code |
Medium | High | High |
-
Severity levels are the same for any type of bank account number—a Basic Bank Account Number (BBAN), an International Bank Account Number (IBAN), or a Canadian or US bank account number.
-
Severity levels are the same for credit card numbers that are or aren't in proximity of a keyword.
If a finding reports multiple types of financial information in an object, Macie determines the finding's severity by calculating the severity for each type of financial information that Macie found, determining which type produces the highest severity, and assigning that highest severity to the finding. For example, if Macie detects 10 credit card expiration dates (Medium severity level) and 10 credit card numbers (High severity level) in an object, Macie assigns a High severity level to the finding.
SensitiveData:S3Object/Personal
A SensitiveData:S3Object/Personal finding indicates that an S3 object contains sensitive personal information—personal health information (PHI), personally identifiable information (PII), or a combination of the two. For this type of finding, Macie determines severity based on the type and number of occurrences of the personal information that Macie found in the object.
The following table indicates the severity levels that Macie assigns to sensitive data findings that report occurrences of PHI in an S3 object.
| Sensitive data type | 1 occurrence | 2–99 occurrences | 100 or more occurrences |
|---|---|---|---|
|
Drug Enforcement Agency (DEA) Registration Number |
High | High | High |
| Health Insurance Claim Number (HICN) | High | High | High |
| Health insurance or medical identification number | High | High | High |
| Healthcare Common Procedure Coding System (HCPCS) code | High | High | High |
| National Drug Code (NDC) | High | High | High |
| National Provider Identifier (NPI) | High | High | High |
| Unique device identifier (UDI) | Low | Medium | High |
The following table indicates the severity levels that Macie assigns to sensitive data findings that report occurrences of PII in an S3 object.
| Sensitive data type | 1 occurrence | 2–99 occurrences | 100 or more occurrences |
|---|---|---|---|
|
Birth date |
Low | Medium | High |
| Driver’s license identification number | Low | Medium | High |
| Electoral roll number | High | High | High |
| Full name | Low | Medium | High |
| Global Positioning System (GPS) coordinates | Low | Medium | Medium |
| HTTP cookie | Low | Medium | High |
| Mailing address | Low | Medium | High |
| National identification number | High | High | High |
| National Insurance Number (NINO) | High | High | High |
| Passport number | Medium | High | High |
| Permanent residence number | High | High | High |
| Phone number | Low | Medium | High |
| Social Insurance Number (SIN) | High | High | High |
| Social Security number (SSN) | High | High | High |
|
Taxpayer identification or reference number |
High | High | High |
|
Vehicle identification number (VIN) |
Low | Low | Medium |
If a finding reports multiple types of PHI, PII, or both PHI and PII in an object, Macie determines the finding's severity by calculating the severity for each type, determining which type produces the highest severity, and assigning that highest severity to the finding.
For example, if Macie detects 10 full names (Medium severity level) and 5 passport numbers (High severity level) in an object, Macie assigns a High severity level to the finding. Similarly, if Macie detects 10 full names (Medium severity level) and 10 health insurance identification numbers (High severity level) in an object, Macie assigns a High severity level to the finding.
SensitiveData:S3Object/Multiple
A SensitiveData:S3Object/Multiple finding indicates that an S3 object contains data spanning multiple sensitive data categories—any combination of credentials data, financial information, personal information, or text that matches the detection criteria of one or more custom data identifiers.
For this type of finding, Macie determines severity by calculating the severity for each type of sensitive data that Macie found (as indicated in the preceding topics), determining which type produces the highest severity, and assigning that highest severity to the finding.
For example, if Macie detects 10 full names (Medium severity level) and 10 AWS secret access keys (High severity level) in an object, Macie assigns a High severity level to the finding.
