Threat Finding

Anomalous Impact Tactic APIs - InvokeModel by AWSReservedSSO_DemoAdministratorAccess_7a819cbf36a34d1f
Priority
P3
Severity
High
ID
a6cc4de4edc...3bc8cdc0486
Assignee
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Status
Open
Resolution
Unresolved
Recommendation
False Positive
Confidence
High
Data Source
Amazon AWS
Finding Source
GuardDuty
Account
934477340168...emo-account)
Exaforce Tags
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GuardDuty Summary

APIs commonly used in Impact tactics were invoked by user AssumedRole : AWSReservedSSO_DemoAdministratorAccess_7a819cbf36a34d1f under unusual circumstances. Such activity is not typically seen from this user.
Exabot Detect
Conclusion
False Positive
High Confidence
This finding represents legitimate business activity by a verified user. Dominik Resl successfully authenticated via SSO from IP 216.9.110.15 at the San Francisco International Airport and immediately accessed AWS Bedrock InvokeModel API. The correlation between SSO login and AWS activity, combined with the read-only nature of InvokeModel operations and widespread organizational use of this API, confirms this is normal business activity during travel. While GuardDuty correctly identified the location as unusual for this user, the proper authentication flow and legitimate business context make this a false positive.

Dominik Resl (dresl@exaforce.com) from Engineering accessed AWS Bedrock InvokeModel API from San Francisco International Airport (AS26231). GuardDuty flagged this as anomalous due to unusual location compared to user's typical Czech Republic locations. However, successful SSO authentication occurred from the same IP address at 00:45:44, just before AWS activity began at 00:46:05. InvokeModel is a commonly used API across the organization with 40+ users and service accounts performing this action. The session chain from IDP to AWS is clean and legitimate.

  • Principal Analysis: The principal is Dominik Resl (dresl@exaforce.com), a legitimate user from the Engineering department with manager Jakub Pavlik. The user accessed AWS through the AWSReservedSSO_DemoAdministratorAccess role, which is a standard SSO-managed administrative role. The user has proper SSO authentication with MFA enabled and shows consistent activity patterns. This is a verified employee with appropriate access permissions and a clean identity profile in the organization's identity provider. The session chain properly flows from IDP user e07c390c-50c1-7018-4fbc-589c201e0a89 to AWS role AROA5TEZQTYEMXSSQ2QS4, indicating legitimate credential usage.
  • Location Analysis: The activity originated from IP address 216.9.110.15 (AS26231 - SFIA-ASN) at San Francisco International Airport, which is geographically distant from the user's typical locations in Czech Republic (Jindřichův Hradec, Prague). However, the user successfully authenticated via SSO from this same IP address at 00:45:44, just one minute before AWS activity began at 00:46:05. This tight timing correlation strongly suggests legitimate travel-based access. Additionally, other company employees (asarakhman) have been observed accessing systems from this same ASN, indicating it's not an unusual location for business travel. The ASN belongs to San Francisco International Airport's network infrastructure, which is a common transit point for international business travel.
  • Session Analysis: The session analysis reveals a clean authentication chain with session ID 9d7ff841-4542-4bbc-a46c-8a704d5b6cfb. The session properly chains from the root IDP session (bda5086b-710f-4312-8144-2084f0fcdd9b) through SAML authentication to the AWS role session. The timing shows SSO login at 00:45:44 followed immediately by AWS access at 00:46:05, indicating normal post-authentication behavior. The session contains 849 events (filtered to 200), predominantly InvokeModel calls to Bedrock service, with some S3 operations and a few Converse API calls. No suspicious session characteristics or anomalous timing gaps were observed.
  • Action Analysis: The flagged action is InvokeModel against AWS Bedrock service, which is a read-only API call used for AI/ML model inference. This user has performed InvokeModel 10 times previously, indicating familiarity with the service. Analysis shows that over 40 other principals in the organization (including both human users like sandesh, sagar, vamshi, arzyk, jpavlik, raj, sli, manjunath, marek, and numerous service accounts) regularly use InvokeModel APIs. The specific model accessed was amazon.titan-embed-text-v2:0, which is used for text embedding generation - a common AI/ML task. All InvokeModel calls were successful (no error codes), and the volume (72 calls) is consistent with typical AI workload patterns.
  • Resource Analysis: The primary resource accessed was the AWS Bedrock foundation model amazon.titan-embed-text-v2:0, which is a legitimate AI service for text embeddings. Additionally, the session included access to S3 bucket demo-exports, which the user has extensive history accessing (over 2000 operations including ListObjects, HeadObject, GetObject, and PutObject). The S3 bucket contains export data, database dumps, and watchtower introspection files - all consistent with legitimate engineering work. The bucket has proper access controls with specific role-based permissions, and the user's access patterns match normal data analysis workflows. No sensitive or unusual resources were accessed outside normal business operations.
  • Behavioral Analysis: The behavioral pattern shows a user accessing familiar AWS services (Bedrock, S3) from an unusual geographic location but following normal authentication and access patterns. The user's historical activity shows regular use of similar services, with InvokeModel being performed 10 times previously and extensive S3 operations. The timing between SSO login and AWS access is consistent with normal user behavior. The volume and type of API calls match legitimate AI/ML development work typical for an Engineering department member. No indicators of automated tool usage, credential compromise, or malicious intent were observed. The activity aligns with normal business operations despite the geographic anomaly.
  • Threat Classification: This is classified as an external threat due to the geographic location being outside the user's normal operating locations. However, the threat level is minimal given the legitimate authentication chain and business context. The 'external' classification stems purely from the location analysis, not from any malicious indicators. The activity represents legitimate business use of AI services by an authenticated employee during travel. No indicators of actual external compromise or malicious external actors were identified. The threat categorization as 'application' reflects the AI service usage rather than any security concern.
  • MITRE Mapping: The finding is mapped to Impact tactic (TA0040) and Resource Hijacking technique (T1496) based on AWS GuardDuty's assessment of unusual AI service usage. However, this mapping appears to be driven by the location anomaly rather than actual malicious resource hijacking. The InvokeModel API calls are legitimate AI inference requests, not resource hijacking attempts. The Impact tactic mapping is likely a conservative classification due to the potential for AI services to be abused for cryptocurrency mining or other resource-intensive activities. In this case, the legitimate business context and proper authentication make actual resource hijacking highly unlikely.
  • Prioritization Analysis: Priority level 3 (low) is assigned based on the high severity classification from GuardDuty, but with a false positive recommendation due to legitimate business context. While the original severity remains high due to the unusual location and AI service usage pattern, the overwhelming evidence of legitimate access through proper authentication channels, combined with normal business usage patterns, significantly reduces the actual risk. The correlation between SSO login and AWS activity from the same IP address, along with the user's legitimate status and common organizational use of these APIs, justifies the low priority classification for response purposes.
  1. Verify with user Dominik Resl (dresl@exaforce.com) that they were traveling through San Francisco International Airport on August 12, 2025, around 00:45 UTC and legitimately accessed AWS Bedrock services for business purposes. Contact can be made directly to the user or through their manager Jakub Pavlik (jpavlik@exaforce.com). Confirm that the AI model usage was for legitimate engineering work and not unauthorized activity. Document the business justification for using AWS Bedrock services from the travel location to establish baseline for future similar scenarios.
  2. Review and potentially tune AWS GuardDuty location-based anomaly detection rules to account for common business travel patterns, particularly for users who regularly work with AI/ML services. Consider implementing allow-listing for major international airports or transit hubs where legitimate business travel is expected. Evaluate whether the current sensitivity settings for Impact tactic APIs are appropriate given the organization's legitimate use of AI services. This may help reduce false positives while maintaining security coverage for actual threats.
  3. Document this incident as a false positive in the security operations knowledge base, including the correlation methodology used between SSO logs and AWS CloudTrail events. Establish standard operating procedures for validating travel-related location anomalies by checking SSO authentication timing and IP address correlation. This will help future analysts quickly identify similar legitimate travel scenarios and reduce investigation time for comparable incidents.
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