AWS IAM API Calls via Temporary Session Tokens

  1[metadata]
  2creation_date = "2025/04/16"
  3integration = ["aws"]
  4maturity = "production"
  5min_stack_version = "9.3.0"
  6min_stack_comments = "Changing min stack to 9.3.0, the latest minimum supported version for 9.X releases."
  7updated_date = "2026/09/18"
  8
  9[rule]
 10author = ["Elastic"]
 11description = """
 12Detects sensitive AWS IAM API operations executed using temporary session credentials (access key IDs beginning with
 13"ASIA"). Temporary credentials are commonly issued through sts:GetSessionToken, sts:AssumeRole, or AWS SSO logins and
 14are meant for short-term use. It is unusual for legitimate users or automated processes to perform privileged IAM
 15actions (e.g., creating users, updating policies, or enabling/disabling MFA) with session tokens. This behavior may
 16indicate credential theft, session hijacking, or the abuse of a privileged role’s temporary credentials.
 17"""
 18false_positives = [
 19    """
 20    Some CI/CD pipelines or administrative users may use session tokens. Review user context, IP, and timing to
 21    validate. This rule automatically excludes console login sessions using the aws.cloudtrail.session_credential_from_console
 22    field, which significantly reduces false positives from legitimate console-based IAM operations.
 23    """,
 24]
 25from = "now-6m"
 26index = ["logs-aws.cloudtrail-*"]
 27language = "kuery"
 28license = "Elastic License v2"
 29name = "AWS IAM API Calls via Temporary Session Tokens"
 30note = """## Triage and analysis
 31
 32### Investigating AWS IAM API Calls via Temporary Session Tokens
 33
 34Temporary session credentials in AWS (identified by access keys beginning with "ASIA") are typically short-lived tokens 
 35issued by the AWS Security Token Service (STS). While they are legitimate and often used by developers or automation pipelines, 
 36their use in direct IAM management or privilege modification is highly unusual and may indicate credential misuse.
 37
 38Attackers who compromise IAM users, roles, or federated identities can obtain session tokens to blend in with normal operations. 
 39They may then execute sensitive IAM API actions such as `CreateAccessKey`, `PutUserPolicy`, or `UpdateAssumeRolePolicy` to 
 40establish persistence, escalate privileges, or disable protections.
 41
 42### Possible investigation steps
 43
 44- **Identify the actor**
 45  - Review `aws.cloudtrail.user_identity.arn` and `aws.cloudtrail.user_identity.type` to determine the originating user or role.
 46  - This rule automatically filters out console login sessions using `aws.cloudtrail.session_credential_from_console`, so alerts indicate non-console temporary credential usage.
 47  - Examine `aws.cloudtrail.user_identity.session_context.mfa_authenticated` — absence of MFA may indicate token misuse.
 48
 49- **Analyze the API context**
 50  - Review `event.action` and `aws.cloudtrail.request_parameters` for the exact IAM operation performed.
 51  - Identify whether the action modifies roles, user policies, trust relationships, or credentials.
 52  - Determine if this session token was associated with prior `sts:GetSessionToken`, `sts:AssumeRole`, or `AWS SSO` events.
 53
 54- **Evaluate source and behavior**
 55  - Inspect `source.ip` and `user_agent.original` for unexpected origins or tools.
 56  - Check if the request came from known infrastructure (e.g., CI/CD nodes, bastion hosts) or an anomalous network.
 57  - Compare `@timestamp` against normal operating hours or deployment schedules.
 58
 59- **Correlate related activity**
 60  - Look for subsequent or preceding activity using the same access key:
 61    - IAM changes (`CreateUser`, `AttachUserPolicy`, `EnableMFADevice`)
 62    - STS operations (`AssumeRole`, `GetCallerIdentity`)
 63    - CloudTrail or GuardDuty configuration changes (possible defense evasion)
 64  - If applicable, search for multiple users exhibiting similar patterns, a sign of large-scale token misuse.
 65
 66### False positive analysis
 67
 68- **Expected automation**
 69  - Some CI/CD pipelines, monitoring tools, or AWS SDK-based automation may perform IAM operations using temporary credentials.
 70  - Validate whether the IAM user or assumed role performing these actions belongs to an authorized automation workflow.
 71- **Administrative operations**
 72  - Security or DevOps engineers may temporarily use session credentials for maintenance or testing.
 73  - Cross-reference with recent change tickets or known operations schedules.
 74- **Federated identity scenarios**
 75  - Federated logins (via AWS SSO or external IdPs) can also generate temporary "ASIA" credentials. Verify if the source identity 
 76    aligns with expected roles or groups.
 77- **Console Login Session**
 78  - Console login sessions are automatically filtered out by this rule using the `aws.cloudtrail.session_credential_from_console` field.
 79
 80### Response and remediation
 81
 82- **Containment**
 83  - If activity is unauthorized, immediately revoke the temporary session by invalidating the associated IAM credentials.
 84  - Rotate long-term credentials (access keys, passwords) for the parent IAM user or role.
 85
 86- **Investigation**
 87  - Search for all actions linked to the same `access_key_id` to assess potential persistence or lateral movement.
 88  - Examine the creation of new users, keys, or policies during or shortly after the detected session.
 89
 90- **Recovery and hardening**
 91  - Require MFA for all privileged actions using `aws:MultiFactorAuthPresent` conditions.
 92  - Implement detection coverage for follow-on persistence actions such as:
 93    - `iam:CreateAccessKey`
 94    - `iam:PutUserPolicy`
 95    - `iam:UpdateAssumeRolePolicy`
 96  - Educate administrative users and developers on secure token handling and the risks of shared credential reuse.
 97
 98### Additional information
 99
100For more information on detecting and mitigating session token abuse:
101- **[AWS Security Token Service (STS) Documentation](https://docs.aws.amazon.com/STS/latest/APIReference/Welcome.html)**
102- **[AWS IR Playbooks](https://github.com/aws-samples/aws-incident-response-playbooks/blob/c151b0dc091755fffd4d662a8f29e2f6794da52c/playbooks/)** 
103- **[AWS Customer Playbook Framework](https://github.com/aws-samples/aws-customer-playbook-framework/tree/a8c7b313636b406a375952ac00b2d68e89a991f2/docs)** 
104- **Security Best Practices:** [AWS Knowledge Center – Security Best Practices](https://aws.amazon.com/premiumsupport/knowledge-center/security-best-practices/).
105"""
106references = ["https://www.sygnia.co/blog/sygnia-investigation-bybit-hack/"]
107risk_score = 73
108rule_id = "c70d9f0d-8cb6-4cfc-85df-a95c1ccf4eab"
109severity = "high"
110tags = [
111    "Domain: Cloud",
112    "Data Source: AWS",
113    "Data Source: Amazon Web Services",
114    "Data Source: AWS CloudTrail",
115    "Data Source: AWS IAM",
116    "Data Source: AWS STS",
117    "Tactic: Persistence",
118    "Tactic: Privilege Escalation",
119    "Resources: Investigation Guide",
120    "Noise: Medium",
121    "Performance: Normal",
122    "Rule Type: New Terms",
123    "Platform: AWS",
124    "Service: AWS IAM",
125    "Service: AWS STS",
126]
127timestamp_override = "event.ingested"
128type = "new_terms"
129
130query = '''
131data_stream.dataset: aws.cloudtrail
132    and event.provider: ("iam.amazonaws.com")
133    and event.outcome: "success"
134    and aws.cloudtrail.user_identity.type: "IAMUser"
135    and aws.cloudtrail.user_identity.access_key_id: ASIA*
136    and source.ip: *
137    and not user_agent.original : "AWS Internal"
138    and not aws.cloudtrail.session_credential_from_console: true
139'''
140
141
142[[rule.threat]]
143framework = "MITRE ATT&CK"
144
145[[rule.threat.technique]]
146id = "T1098"
147name = "Account Manipulation"
148reference = "https://attack.mitre.org/techniques/T1098/"
149
150[rule.threat.tactic]
151id = "TA0003"
152name = "Persistence"
153reference = "https://attack.mitre.org/tactics/TA0003/"
154
155[[rule.threat]]
156framework = "MITRE ATT&CK"
157
158[[rule.threat.technique]]
159id = "T1078"
160name = "Valid Accounts"
161reference = "https://attack.mitre.org/techniques/T1078/"
162
163[[rule.threat.technique.subtechnique]]
164id = "T1078.004"
165name = "Cloud Accounts"
166reference = "https://attack.mitre.org/techniques/T1078/004/"
167
168[rule.threat.tactic]
169id = "TA0005"
170name = "Defense Evasion"
171reference = "https://attack.mitre.org/tactics/TA0005/"
172[rule.investigation_fields]
173field_names = [
174    "@timestamp",
175    "user.name",
176    "user_agent.original",
177    "source.ip",
178    "aws.cloudtrail.user_identity.arn",
179    "aws.cloudtrail.user_identity.type",
180    "aws.cloudtrail.user_identity.access_key_id",
181    "event.action",
182    "event.outcome",
183    "cloud.account.id",
184    "cloud.region",
185    "aws.cloudtrail.request_parameters",
186]
187
188[rule.new_terms]
189field = "new_terms_fields"
190value = ["aws.cloudtrail.user_identity.arn"]
191[[rule.new_terms.history_window_start]]
192field = "history_window_start"
193value = "now-7d"