Your network might be compromised right now, and you don't even know it. The average time to detect a breach is still measured in months, giving attackers plenty of time to steal data, deploy ransomware, or establish persistent access to your systems.
But compromised networks leave telltale signs—if you know what to look for. Here are 10 critical indicators that your network security has been breached, and what you should do about each one.
1. Unusual Outbound Traffic Patterns
The Warning Sign
Sudden spikes in outbound data transfer, especially during off-hours or to unfamiliar destinations, often indicate data exfiltration.
What It Means
Attackers typically compress and encrypt stolen data before transmission. This creates distinctive traffic patterns—large volumes of data flowing to unusual IP addresses or geographic locations.
What to Do
- Immediately investigate the source systems
- Block suspicious destination IPs
- Review recent file access logs
- Check for unauthorized data compression or encryption tools
How Purplerain Tech Helps
Our network nodes establish baseline traffic patterns for every device. Any deviation—like a workstation suddenly uploading gigabytes of data at 3 AM—triggers instant alerts with full context about the anomaly.
2. Multiple Failed Login Attempts Followed by Success
The Warning Sign
Repeated failed authentication attempts from the same source, followed by a successful login, suggests credential stuffing or brute force attacks.
What It Means
Attackers are testing stolen or guessed credentials. A successful login after many failures indicates they've gained access.
What to Do
- Immediately disable the compromised account
- Force password resets for affected users
- Review account activity for unauthorized actions
- Implement multi-factor authentication if not already in place
How Purplerain Tech Helps
Our behavioral analysis flags unusual authentication patterns in real-time, stopping attackers before they can leverage compromised credentials.
3. Unexpected Administrative Account Creation
The Warning Sign
New user accounts, especially with administrative privileges, that weren't created through your normal provisioning process.
What It Means
Attackers create backdoor accounts to maintain persistent access even if their initial entry point is discovered and closed.
What to Do
- Immediately disable suspicious accounts
- Review all recent account creations
- Audit administrative group memberships
- Implement approval workflows for privileged account creation
How Purplerain Tech Helps
Nodes monitor Active Directory and authentication systems, alerting on any account modifications that deviate from established patterns.
4. Disabled or Modified Security Tools
The Warning Sign
Antivirus software, firewalls, or logging systems suddenly disabled, uninstalled, or configured to ignore certain files or processes.
What It Means
Sophisticated attackers disable security tools to operate undetected. This is often one of the first actions after gaining initial access.
What to Do
- Assume active breach and initiate incident response
- Re-enable security tools from clean systems
- Review logs before they were disabled
- Scan all systems with known-good security tools
How Purplerain Tech Helps
Our nodes operate independently of endpoint security tools. Even if attackers disable antivirus or firewalls, network-level monitoring continues uninterrupted.
5. Unusual Lateral Movement
The Warning Sign
Systems or users accessing resources they don't normally use, especially administrative shares, domain controllers, or sensitive databases.
What It Means
After compromising one system, attackers move laterally across your network to find valuable data or gain higher privileges.
What to Do
- Isolate affected systems immediately
- Review authentication logs for the movement path
- Identify and secure the initial compromise point
- Implement network segmentation to limit lateral movement
How Purplerain Tech Helps
Distributed nodes see all internal traffic, immediately flagging unusual system-to-system communications that indicate lateral movement.
6. Unexplained System Performance Degradation
The Warning Sign
Servers or workstations experiencing slowdowns, crashes, or resource exhaustion without apparent cause.
What It Means
Malware, especially cryptocurrency miners or data exfiltration tools, consumes system resources. Performance issues may also indicate DDoS preparation or botnet activity.
What to Do
- Monitor resource usage to identify suspicious processes
- Check for unauthorized software installations
- Review network connections from affected systems
- Scan for malware with multiple tools
How Purplerain Tech Helps
Nodes correlate performance issues with network behavior, distinguishing between legitimate load and malicious activity.
7. DNS Query Anomalies
The Warning Sign
Unusual DNS queries, especially to newly registered domains, suspicious TLDs, or algorithmically generated domain names.
What It Means
Many malware families use DNS for command-and-control communication or data exfiltration. Unusual DNS patterns are strong indicators of compromise.
What to Do
- Block suspicious domains immediately
- Identify systems making unusual queries
- Review DNS logs for patterns
- Implement DNS filtering and monitoring
How Purplerain Tech Helps
Our nodes analyze DNS traffic patterns, identifying command-and-control communication and DNS tunneling attempts in real-time.
8. Unexpected File System Changes
The Warning Sign
Mass file modifications, especially encryption or deletion of backup files, documents being renamed with unusual extensions, or new executable files appearing in system directories.
What It Means
This often indicates ransomware deployment. Attackers typically delete or encrypt backups first to maximize leverage.
What to Do
- Immediately disconnect affected systems from the network
- Do NOT pay ransom or delete encrypted files
- Restore from offline backups if available
- Engage incident response professionals
How Purplerain Tech Helps
Nodes detect the network traffic patterns associated with ransomware deployment, often catching attacks before encryption begins.
9. Unusual Database Queries
The Warning Sign
Large-scale database queries, especially those accessing entire tables or sensitive fields, that don't match normal application behavior.
What It Means
Attackers are likely extracting data for theft or sale. This is particularly concerning for customer data, financial records, or intellectual property.
What to Do
- Identify the source of unusual queries
- Review database access logs
- Implement query monitoring and anomaly detection
- Restrict database access to minimum necessary privileges
How Purplerain Tech Helps
By monitoring network traffic to database servers, our nodes identify unusual query patterns and data transfer volumes that indicate data theft.
10. Alerts from External Sources
The Warning Sign
Notifications from customers, partners, security researchers, or law enforcement that your systems are involved in malicious activity.
What It Means
Your compromise is severe enough that external parties have noticed. This often indicates your systems are being used for spam, phishing, or attacks against others.
What to Do
- Take external reports seriously
- Immediately investigate reported indicators
- Engage incident response team
- Prepare for potential public disclosure
How Purplerain Tech Helps
Our proactive monitoring aims to detect compromises before external notification, giving you time to respond privately and minimize damage.
The Importance of Automated Detection
Manually monitoring for these signs across a modern network is impossible. You need automated, intelligent monitoring that:
Establishes Baselines
Understands what "normal" looks like for your specific environment.
Detects Anomalies
Identifies deviations from baseline behavior in real-time.
Correlates Events
Connects seemingly unrelated indicators to identify sophisticated attacks.
Provides Context
Delivers actionable intelligence, not just raw alerts.
Scales Effortlessly
Monitors growing networks without proportional increases in security staff.
Purplerain Tech: Automated Indicator Detection
Our network security nodes are specifically designed to detect all ten of these compromise indicators automatically:
- Traffic Analysis: Identifies unusual data flows and exfiltration attempts
- Behavioral Monitoring: Flags authentication anomalies and lateral movement
- System Observation: Detects security tool tampering and performance issues
- DNS Intelligence: Analyzes DNS patterns for command-and-control activity
- Database Protection: Monitors database access and query patterns
Most importantly, our nodes work together to correlate these indicators, distinguishing between isolated anomalies and coordinated attacks.
Don't Wait for Confirmation
If you're seeing multiple indicators from this list, assume you're compromised and act immediately:
- Activate incident response procedures
- Isolate affected systems
- Preserve evidence
- Engage security professionals
- Notify stakeholders as appropriate
The cost of assuming a false positive is minimal compared to the cost of ignoring a real breach.
Prevention Through Continuous Monitoring
The best way to handle these compromise indicators? Detect them automatically before they become full-blown breaches.
Purplerain Tech's node-based monitoring provides the continuous visibility and intelligent analysis needed to catch attacks in their earliest stages—often before attackers can accomplish their objectives.
Ready to stop playing catch-up with cybercriminals? Discover how Purplerain Tech can detect compromise indicators automatically, giving you the early warning you need to protect your business.