Date: April 12, 2025
The security investigation has identified two distinct patterns of high-severity network activity that warrant attention. The first pattern involves highly regular communications between an internal host (192.168.50.71) and Ubuntu repositories using obsolete nginx servers (versions 1.14.0/1.18.0), occurring at consistent 5-minute intervals with nearly identical data volumes. The second pattern shows irregular communications between host 192.168.50.189 and Apple CDN servers with unusual protocol characteristics, failed connection attempts, and asymmetric data transfers.
The Ubuntu repository communications (Pattern 1) are likely legitimate system updates or maintenance processes, but present security concerns due to the outdated components and consistently missing User-Agent headers. These vulnerabilities could potentially be exploited even if the current activity is benign. We assess with high confidence that this represents automated system maintenance rather than malicious activity, though the security vulnerabilities require remediation.
The Apple CDN communications (Pattern 2) present more complex characteristics including unusual port usage (TLS on port 80), connection failures, and anomalous protocol identifiers. This could represent either a misconfigured application, mobile device synchronization issues, or potentially concerning data movement. The 5:1 ratio of outbound to inbound data warrants closer investigation.
Major information gaps include process ownership details, application inventory context, and historical baseline data that would help distinguish between normal operations and security incidents.
Recommended next steps include: inspecting the Ubuntu update mechanisms, analyzing full packet content of Apple communications, implementing enhanced monitoring for protocol anomalies, and updating the obsolete nginx components regardless of whether malicious intent is confirmed.
Based on the analysis of high-severity alerts (score ≥ 100) since April 12, 2025, at 07:18:19 UTC, a significant pattern of activity has been observed within the network. All alerts show a maximum severity score of 150, indicating critical security concerns that warrant immediate investigation.
The data reveals concentrated activity originating primarily from two internal IP addresses (192.168.50.71 and 192.168.50.189), which account for the majority of high-severity alerts. These internal hosts are communicating with multiple external destinations, generating a total of 150 high-severity alerts across the analyzed connections.
The most prevalent alert types observed are:
Most of the connections involve the internal IP 192.168.50.71 communicating with multiple external IPs in the 185.125.190.x and 91.189.91.x ranges. The secondary pattern involves 192.168.50.189 communicating with 17.253.x.x IP addresses and showing evidence of TCP connection activities.
There is also internal communication between 192.168.50.55 and 192.168.50.189 generating high-severity alerts related to User-Agent headers on port 80.
This pattern represents the most significant cluster of alerts, with a single internal host (192.168.50.71) communicating with multiple external destinations. All communications generate high-severity alerts related to obsolete nginx server versions and missing User-Agent headers.
This pattern shows activity from 192.168.50.189 to Apple-owned IP addresses (17.253.x.x range) with alerts indicating TCP probing attempts, connection refusals, and missing User-Agent headers across multiple ports.
This pattern represents internal network communications generating high-severity alerts related to HTTP traffic with missing User-Agent headers on port 80, indicating potential internal reconnaissance or unauthorized communication between hosts within the protected network.
The traffic shows a remarkably consistent pattern with nearly identical byte counts across all communications. Connections occur at regular intervals throughout the day, suggesting automated, scheduled communications. The destination IPs belong to Canonical, the company behind Ubuntu Linux. Source ports appear to be randomly allocated high ports, while destination ports are consistently 80.
This pattern likely represents Ubuntu update checks or repository communications using outdated software. The obsolete nginx server versions (1.14.0 and 1.18.0) are notable security concerns as they may contain known vulnerabilities.
The consistent "Empty or missing User-Agent" in communications to Ubuntu servers could indicate:
The periodic nature suggests scheduled tasks rather than interactive user activity. Given that these are connections to legitimate Ubuntu servers, this may represent standard system maintenance processes using outdated components rather than malicious activity.
The communications alternate between connection attempts that are refused and successful connections with substantial data transfer. The traffic shows irregular timing rather than the consistent periodicity seen in Pattern 1.
This pattern presents several unusual characteristics that warrant investigation:
Canonical Group Limited is the company behind Ubuntu Linux, one of the most widely-used Linux distributions. They maintain numerous servers worldwide to support Ubuntu update repositories, software distribution networks, and cloud services. The company was founded in 2004 by Mark Shuttleworth and is headquartered in London, UK.
The observed traffic pattern shows highly consistent, automated communications occurring at precisely timed 5-minute intervals with almost identical byte counts across sessions. This pattern strongly indicates scheduled system tasks rather than interactive or human-initiated communication.
The observed traffic is likely legitimate Ubuntu system updates or repository checks occurring on a scheduled basis. However, the presence of obsolete nginx server versions (1.14.0/1.18.0) represents a significant security concern as these versions contain known vulnerabilities that could be exploited.
The missing User-Agent headers in all communications are unusual for legitimate Ubuntu update processes, which typically include identifiable User-Agent strings. This could indicate:
Recommendation: Update the nginx server components to the latest version and investigate why User-Agent headers are missing from these communications. Implement egress filtering rules to monitor traffic to these destinations for any deviations from the established pattern.
Apple Inc. is a multinational technology company headquartered in Cupertino, California. The IPs in question belong to Apple's content delivery network (aaplimg.com domain), which hosts various Apple services including software updates, iCloud services, and app store content. AS6185 is a long-established Apple autonomous system (registered in 1995).
The traffic pattern shows irregularly timed connections with a mix of successful and failed connection attempts. The asymmetric data transfer ratio (significantly more outbound than inbound data) and unusual port usage (TLS traffic on port 80 instead of 443) indicate potential misconfiguration or non-standard behavior.
The association with "HTTP_Connect, GoogleServices" protocol is unusual for Apple infrastructure and could indicate proxy tunneling attempts through Apple's CDN infrastructure.
The irregular connection patterns, failed connection attempts, and anomalous protocol behavior represent potentially concerning activity that warrants immediate investigation.
The network traffic between 192.168.50.71 and Canonical Group Limited servers (185.125.190.x and 91.189.91.x) displays a highly consistent, periodic pattern. Communications occur at remarkably regular 5-minute intervals. Each connection is brief, with nearly identical timing characteristics. There is no observable variation in connection timing based on time of day.
The data transfer volumes show extreme consistency:
This consistency in byte count (varying by less than 5%) across all communications indicates automated, template-based communications rather than human-initiated or content-variable transfers.
The traffic is remarkably symmetric, with inbound and outbound bytes nearly equal in volume. This is unusual for normal HTTP communications, which typically have asymmetric response-to-request ratios.
The observed pattern strongly indicates an automated update check or scheduled service communication to Ubuntu-related servers. The extreme regularity (5-minute intervals) and consistent byte counts suggest:
The empty User-Agent headers consistently present in these communications are unusual but could be explained by either a simple configuration oversight or a deliberate attempt to minimize identifiable information in regular communications.
The traffic between 192.168.50.189 and Apple servers (17.253.x.x range) shows irregular timing with two distinct sub-patterns:
Unlike Pattern 1, there is no regular periodicity. Multiple connection attempts often occur in clusters (3-5 attempts within a few seconds), followed by periods of inactivity.
The data volumes show significant variation:
The most striking characteristic is the asymmetric data volumes in successful connections, with outbound data (25,000+ bytes) significantly exceeding inbound data (5,500 bytes) - a nearly 5:1 ratio.
Successful connections show significant asymmetry with 4-5 times more outbound than inbound data, suggesting data retrieval rather than submission.
This pattern exhibits characteristics of both legitimate application behavior and potential security concerns.
Security incidents often have non-malicious explanations that may be overlooked during initial analysis. This section evaluates plausible benign interpretations for each observed pattern, assesses evidence strength, and identifies information gaps that need to be addressed.
The consistent 5-minute intervals to Canonical servers strongly suggest this is an automated update check mechanism from an Ubuntu system. The byte count consistency (355-419 bytes inbound, 401-405 bytes outbound) matches the profile of repository index checking rather than malicious activity. The missing User-Agent could simply be a configuration oversight in the update client.
This could be a legacy internal application that was built using older nginx components and hasn't been updated due to compatibility concerns or resource constraints. The application may be performing regular health checks or data synchronization with Ubuntu repositories. The 5-minute cron job timing is common for monitoring systems.
This could represent a development or testing environment where outdated components are deliberately used to match production environments elsewhere. The traffic might be test cases being run against Ubuntu repositories to validate functionality without concern for security in a sandboxed environment.
The irregular timing, connection failures, and Apple server communications strongly suggest an iOS device experiencing synchronization issues. The unusual port usage and HTTP_Connect protocol with "GoogleServices" could indicate a third-party app attempting to use Google services via Apple's infrastructure, with connection reset patterns typical of retry logic when networks are unstable.
The varied protocols, connection attempts, and mix of successful/failed connections could be from a legitimate network monitoring tool checking connectivity to critical services. The tool might be configured to use non-standard ports to test routing policies or firewall rules, with the "TCP probing" representing normal functionality rather than an attack.
A cloud-native application with incorrect configuration might be attempting to connect to Apple services on wrong ports or with incorrect protocols. The asymmetric data volumes (5:1 ratio of outbound to inbound) suggest content download rather than data exfiltration.
To increase assessment confidence, the following additional data would be valuable:
These alternative explanations don't eliminate security concerns, particularly the obsolete nginx versions, but they provide reasonable non-malicious interpretations
Overall Severity: MEDIUM (Medium-High Confidence)
The network activity presents legitimate security concerns balanced with probable benign explanations. Based on comprehensive analysis of alert patterns, IP intelligence, timing characteristics, and alternative interpretations, this assessment identifies two primary activity clusters requiring different response approaches.
The highly regular 5-minute interval communications between 192.168.50.71 and Canonical Group Limited servers (Ubuntu repositories) demonstrate classic characteristics of automated system processes rather than malicious activity. The perfect regularity, consistent byte counts (355-419 bytes inbound, 401-405 bytes outbound), and legitimate destination servers strongly suggest scheduled update checks or system maintenance.
However, significant security concerns exist despite the likely benign purpose:
Most probable explanation: The pattern represents scheduled Ubuntu system maintenance using outdated components that should be updated but does not indicate compromise.
Communications between 192.168.50.189 and Apple CDN infrastructure present more concerning characteristics, including irregular timing, connection failures, unusual port usage (TLS on port 80), and the anomalous presence of "HTTP_Connect, GoogleServices" protocol identifiers when connecting to Apple infrastructure.
The 5:1 ratio of outbound to inbound data could represent either:
Unlike Pattern 1, this traffic lacks the consistent predictability of scheduled system tasks and shows characteristics consistent with both application misbehavior and potential security incidents.
If security concerns are valid:
In context of typical network behavior, the Ubuntu repository traffic follows expected patterns for automated system processes but uses vulnerable components. The Apple communications show multiple anomalies that deviate from expected application behavior but could be explained by misconfiguration or mobile device synchronization issues.
This assessment balances security concerns with probable benign explanations, acknowledging that definitive conclusions require further investigation to fill critical information gaps regarding application inventory, process ownership, and historical baselines.
Examine the automated update processes on 192.168.50.71 to verify whether they're using obsolete nginx components. Check system logs during 5-minute intervals to confirm process ownership of the Canonical communications.
Rationale: Pattern 1 shows consistent 5-minute interval connections to Ubuntu servers, likely benign but using vulnerable components.
Monitor and capture full packet content (where legal) of communications between 192.168.50.189 and Apple CDN servers. Verify device type and installed applications associated with 192.168.50.189.
Rationale: Pattern 2 shows irregular timing, unusual port usage, and mixed protocols that need verification before taking disruptive action.
Compare current communication patterns with historical network data to determine if these traffic patterns are new or long-standing. Review endpoint inventory to confirm expected OS types and applications on the flagged internal IPs.
Rationale: Both patterns require baseline context to distinguish between normal operations and potential security incidents.
Create monitoring rules to log (but not block) communications with unusual characteristics such as missing User-Agent headers. Apply destination-specific traffic rate limiting for connections to Ubuntu and Apple servers from the identified hosts.
Rationale: Addresses the empty User-Agent headers in Pattern 1 and irregular timing in Pattern 2 without disrupting legitimate operations.
Implement session monitoring for the traffic between 192.168.50.189 and Apple servers, focusing on the HTTP_Connect protocol. Configure alerts for protocol/port mismatches (e.g., TLS on port 80) and connection pattern changes.
Rationale: Pattern 2's irregular timing and unusual protocol/port combinations require close monitoring.
Run targeted vulnerability scans on 192.168.50.71 to identify outdated nginx components and other potential vulnerabilities. Perform endpoint security scans on 192.168.50.189 to check for signs of compromise.
Rationale: Addresses the obsolete nginx server alerts in Pattern 1 and potential security concerns in Pattern 2.
Identify and document which specific processes are initiating the connections to Canonical and Apple servers. Validate that these processes are legitimate and expected on these systems.
Rationale: Process identification will clarify whether Pattern 1 is legitimate Ubuntu updates and Pattern 2 is an expected application.
Cross-reference active applications with observed traffic patterns to identify which applications may be generating the traffic. Interview system owners regarding expected behavior of applications on these hosts.
Rationale: Both patterns could be explained by legitimate but misconfigured applications.
Examine the content of the asymmetric data transfers in Pattern 2 (5:1 outbound to inbound ratio). Compare byte patterns in Pattern 1 communications against known Ubuntu update mechanisms.
Rationale: Determines whether data transfer characteristics match expected application behavior or indicate potential exfiltration.
Schedule updates for the obsolete nginx servers (versions 1.14.0/1.18.0) identified in Pattern 1. Test updates in a controlled environment before deploying to production systems.
Rationale: Addresses the concrete security vulnerability of outdated nginx components regardless of malicious intent.
Reconfigure applications to use appropriate ports and protocols if investigation confirms misconfiguration. Fix User-Agent header settings in automated update processes if legitimate.
Rationale: Resolves the protocol anomalies in Pattern 2 and User-Agent issues in Pattern 1 if found to be configuration issues.
Deploy permanent monitoring for empty User-Agent headers and unusual protocol/port combinations. Create automated alerts for communication pattern changes to quickly identify deviations.
Rationale: Provides sustainable visibility into network behaviors that triggered the initial alerts.