3.77.221.157📋 Copy

# IP Intelligence Briefing: 3.77.221.157/32

Date: 2026-06-19

Classification: Threat Intelligence

Risk Level: Moderate (Score: 50/100)

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## Executive Summary

IP address 3.77.221.157 is a cloud infrastructure endpoint belonging to Amazon Web Services (AWS), hosted in the Frankfurt region (eu-central-1). The IP presents a moderate risk profile with no confirmed malicious activity detected. The endpoint is associated with AWS EC2 infrastructure and shows evidence of blacklist listings. Despite the cloud provider association, the IP has been flagged by threat intelligence sources, warranting defensive monitoring.

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## Technical Profile

Network Identity:

• ASN: 16509 (Amazon.com, Inc.)
• Organization: A100 ROW GmbH
• Geolocation: Frankfurt, Germany (50.11°N, 8.68°E)
• Region: eu-central-1 (AWS Frankfurt)
• CIDR: 3.64.0.0/12

DNS Resolution:

• PTR Hostname: ec2-3-77-221-157.eu-central-1.compute.amazonaws.com
• Forward Resolution: Confirmed (amazonaws.com)
• Status: Active EC2 instance

Network Services:

• Open Ports: None detected
• Service Banner: No services exposed
• Connection Type: Firewalled / No Services

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## Threat Indicators

Current Risk Assessment:

• Risk Score: 50/100 (Moderate)
• Abuse Confidence: Data unavailable
• Blacklist Status: Listed on 1 of 8 DNSBLs
• Known Attack Source: No
• Spam Source: No
• Tor Exit Node: No

Threat Persistence:

• Observation Count: 1
• Persistence Days: 0
• Persistently Malicious: No

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## Historical Signal Analysis

Observation Timeline (2026-06-18 to 2026-06-19):

• 29 total observations recorded
• Multiple ASN and prefix resolution events documented
• One high-severity blacklist listing observed on 2026-06-19
• Geographic resolution inconsistencies noted (US vs DE)
• Prefix variations observed: 3.64.0.0/10, 3.64.0.0/12

Temporal Indicators:

• Ownership changes: 0
• Threat observation count: 1
• No evidence of persistent malicious behavior

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## Network Relationships

Identified Associations:

• 71 total relationships detected
• DNS associations to ec2-3-77-221-157.eu-central-1.compute.amazonaws.com
• Network association: AMAZON-FRA (AWS Frankfurt facility)
• Multiple hostname associations (repeated entries)

Campaign Correlation:

• Likelihood: None
• CERT Matches: 0
• Correlated IPs: 0
• Campaign matches: 0

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## Subnet Analysis

Neighborhood: 3.77.221.157/24

• Abuse Density: 0
• Classification: mostly_clean
• Inherited Risk: 2
• Active Siblings: 1
• Threat Siblings: 1
• Neighbor Count: 0

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## Recommended Security Actions

Immediate Actions:

• iPTables: `iptables -A INPUT -s 3.77.221.157 -j DROP`
• nftables: `nft add rule inet filter input ip saddr 3.77.221.157 drop`
• Nginx: `deny 3.77.221.157;`
• pfSense: `3.77.221.157/32`
• Cloudflare WAF: Block with expression `ip.src eq 3.77.221.157`
• AWS WAF: Add 3.77.221.157/32 to IP set

Risk-Based Recommendations:

The moderate risk score combined with DNSBL listings suggests this IP should be monitored and potentially blocked. However, given the AWS infrastructure association, consider allowing the IP through if it matches known legitimate service patterns, or implement rate limiting instead of outright blocking.

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## Assessment & Intelligence Notes

The IP 3.77.221.157 represents a cloud endpoint with moderate threat indicators. While the absence of open ports and known attack indicators suggests potential legitimate infrastructure use, the presence of blacklist listings and moderate risk classification warrants defensive posture. The IP should be included in threat intelligence monitoring but does not require immediate blocking without additional contextual signals. SOC teams should evaluate against internal traffic patterns and consider the cloud provider association when determining response actions.

This summary was generated by AI and may contain inaccuracies. Verify critical details independently.