Many AccessDenied Errors from Single Source

Status: test
Severity: high
Time window: 10m
Log source: product aws, service cloudtrail
Author: nishikawaakira (@nishikawaakira)
Source: github.com/Yamato-Security/suzaku-rules

Detects multiple authorization failure errors from the same source IP and access key within a short time window. This pattern indicates an attacker probing AWS APIs with stolen credentials that have restricted permissions. Covers both IAM-level AccessDenied and EC2-style Client.UnauthorizedOperation. Attackers who obtain credentials via SSRF, leaked .env files, or code repositories typically enumerate dozens of AWS APIs to discover what they can access.

MITRE ATT&CK coverage

Tactic	Techniques
Discovery	`T1580` Cloud Infrastructure Discovery

Rule body yaml

title: Many AccessDenied Errors from Single Source
id: 4a6b8c0d-2e3f-5a7b-9c1d-3e4f5a6b7c8d
status: test
description: |
    Detects multiple authorization failure errors from the same source IP and
    access key within a short time window. This pattern indicates an attacker
    probing AWS APIs with stolen credentials that have restricted permissions.
    Covers both IAM-level AccessDenied and EC2-style Client.UnauthorizedOperation.
    Attackers who obtain credentials via SSRF, leaked .env files, or code
    repositories typically enumerate dozens of AWS APIs to discover what they
    can access.
references:
    - https://attack.mitre.org/techniques/T1580/
    - https://hackingthe.cloud/aws/general-knowledge/using_stolen_iam_credentials/
author: nishikawaakira (@nishikawaakira)
date: 2026-05-03
modified: 2026-05-29
tags:
    - attack.discovery
    - attack.t1580
logsource:
    product: aws
    service: cloudtrail
correlation:
    type: event_count
    rules:
        - AccessDenied Error
    group-by:
        - sourceIPAddress
        - userIdentity.accessKeyId
    timespan: 10m
    condition:
        gte: 10
    generate: false
level: high
---
title: AccessDenied Error
id: 4a6b8c0d-2e3f-5a7b-9c1d-3e4f5a6b7c8e
status: test
description: Base rule for AccessDenied correlation.
references:
author: nishikawaakira (@nishikawaakira)
date: 2026-05-03
modified: 2026-05-29
tags:
    - attack.discovery
logsource:
    product: aws
    service: cloudtrail
detection:
    selection:
        errorCode:
            - AccessDenied
            - Client.UnauthorizedOperation
    condition: selection
level: informational

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    errorCode:
        - AccessDenied
        - Client.UnauthorizedOperation

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
`errorCode`	eq	`AccessDenied` `Client.UnauthorizedOperation`

`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
`Esc`	Close results / dialog

`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)

Many AccessDenied Errors from Single Source

MITRE ATT&CK coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Indicators

Keyboard shortcuts

Search operators

Many AccessDenied Errors from Single Source

MITRE ATT&CK coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection

Indicators

Stage 0: `condition`

Stage 1: `selection`