AWS EC2 EBS Encryption Disabled

Severity: medium
Log types: AWS.CloudTrail
Reference: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EBSEncryption.html#encryption-by-default
Source: github.com/panther-labs/panther-analysis

Identifies disabling of default EBS encryption. Disabling default encryption does not change the encryption status of existing volumes.

MITRE ATT&CK coverage

Tactic	Techniques
Impact	`T1486` Data Encrypted for Impact, `T1565` Data Manipulation

Rules detecting the same action

Other rules on this platform that filter on the same API call or operation.

AWS EC2 Disable EBS Encryption (Sigma)
AWS EC2 Encryption Disabled (Elastic)

Rule body yaml

AnalysisType: rule
Description: "Identifies disabling of default EBS encryption. Disabling default encryption does not change the encryption status of existing volumes. "
DisplayName: "AWS EC2 EBS Encryption Disabled"
Enabled: true
Filename: aws_ec2_ebs_encryption_disabled.py
Reports:
  MITRE ATT&CK:
    - TA0040:T1486
    - TA0040:T1565
Runbook: Verify this action was intended and if any EBS volumes were created after the change.
Reference: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EBSEncryption.html#encryption-by-default
Severity: Medium
Tests:
  - ExpectedResult: true
    Log:
      awsRegion: us-east-1
      eventName: DisableEbsEncryptionByDefault
      eventSource: ec2.amazonaws.com
      recipientAccountId: "123456789"
      sourceIPAddress: 1.2.3.4
      userAgent: Chrome Browser
    Name: DisableEbsEncryptionByDefault Event
  - ExpectedResult: false
    Log:
      awsRegion: ap-northeast-1
      eventName: DescribeInstanceStatus
      eventSource: ec2.amazonaws.com
      eventTime: "2022-09-25 16:16:37"
      eventType: AwsApiCall
      readOnly: true
      sourceIPAddress: 1.2.3.4
      userAgent: Datadog
    Name: Non Matching Event
DedupPeriodMinutes: 60
LogTypes:
  - AWS.CloudTrail
RuleID: "AWS.EC2.EBS.Encryption.Disabled"
Threshold: 1

Detection logic

Condition

eventSource eq "ec2.amazonaws.com"
eventName eq "DisableEbsEncryptionByDefault"

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`eventName`	eq	`DisableEbsEncryptionByDefault`
`eventSource`	eq	`ec2.amazonaws.com`

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

Field
`eventName`
`eventSource`
`awsRegion`
`recipientAccountId`
`sourceIPAddress`
`userAgent`
`userIdentity`

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
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`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)