Signs Your Company Network Has Been Hacked - And What to Do About It
- Neil Hare-Brown
- 6 days ago
- 2 min read
In today’s threat landscape, most cyber attacks go undetected for weeks or even months.
Attackers are becoming stealthier, and many businesses don’t realise their network has been breached until it’s too late - often when ransomware is deployed or customer data surfaces online.
At STORM Guidance, we help businesses identify, investigate, and respond to suspected network compromises. This guide highlights the warning signs of a hack, how to confirm a breach, and the steps you should take immediately.
Common Signs Your Network Has Been Compromised
1. Unusual Login Activity
Logins from unfamiliar locations, devices, or IPs
Out-of-hours access by staff or service accounts
Multiple failed login attempts followed by a successful one
2. Unexpected Software or Tools Running
Unauthorised installations of remote access tools (e.g. TeamViewer, AnyDesk)
Scripts or command-line tools running without explanation
Unknown processes consuming large amounts of system resources
3. Suspicious Network Traffic
High outbound data transfers, especially outside business hours
Communication with known malicious IP addresses or foreign servers
Use of unusual ports or encrypted tunnels you didn’t configure
4. Antivirus or Security Tools Disabled
Endpoint protection is suddenly deactivated or uninstalled
Alerts are turned off without admin approval
Logs are missing or system events have been wiped
5. New or Altered Admin Accounts
Unauthorised user accounts with elevated privileges
Changes to group policies, firewall rules, or file access permissions
Creation of "backdoor" accounts with generic names
6. Ransom Notes or Data Encryption
Files are renamed or encrypted, with extensions like .locked, .encrypted, etc.
A ransom demand appears on-screen or in each affected directory
Access to file shares or systems is suddenly lost
🚨 If you notice more than one of these signs, your network may already be compromised.
What to Do If You Suspect a Hack
✅ 1. Don’t Ignore It - Act Immediately
Suspicious behaviour should be treated seriously, even if you're unsure. The sooner you respond, the more you can contain. If you have a cyber incident response plan, trigger it!
✅ 2. Isolate Affected Systems
Disconnect suspected machines from the network (not just Wi-Fi). If possible, avoid powering off systems-volatile memory may be needed for forensics.
✅ 3. Contact a Cyber Incident Response Specialist
Engage a trusted partner like STORM Guidance to:
Analyse signs of compromise
Help contain and investigate the breach
Guide next steps (including legal, regulatory, and recovery actions)
✅ 4. Notify Internal Stakeholders
Involve your IT/security team, senior leadership, and legal/compliance teams. Be prepared to coordinate internal messaging and external communications if needed.
How STORM Guidance Can Help
✔ Forensic investigation and threat detection
✔ Containment and recovery from active cyber threats
✔ Regulatory guidance for GDPR, ICO, and industry-specific reporting
✔ Long-term resilience planning and breach prevention
Know the Signs. Reduce the Risk
The earlier you detect a breach, the easier it is to limit the fallout.
Don’t wait for ransom notes or leaked data to appear online. Train your team to spot the signs, prepare your systems to respond, and partner with experts who can guide you through it all.
STORM Guidance is here to help you uncover hidden threats, contain incidents, and build lasting cyber resilience.
