A timely response to a cybersecurity incident can mean the difference between a minor inconvenience and a full-blown crisis. Unfortunately, organizations take an average of 194 days just to identify that they’ve been breached, and it then takes another 64 days to contain the damage.
So, how can you avoid becoming part of that statistic? By vigilantly keeping an eye out for the following key indicators of compromise, which are telltale signs and anomalies that suggest unauthorized access or malicious activity in your systems.
The Most Common Signs You Have Been Hacked
Hackers don’t want to get caught in the act. Instead, they want to quietly infiltrate your systems, steal valuable data, and potentially set up backdoors for future access—all while flying under your radar. That’s why many of the warning signs that someone may have compromised your organization’s security are subtle and easy to dismiss.
1. Unexplained Failed Login Attempts
If you notice an unusual number of failed login attempts showing up in your security logs, then it’s possible that hackers are trying to brute force their way into your systems by systematically testing different password combinations until they find one that works.
While brute force attacks are difficult to prevent entirely due to their persistent nature, you can dramatically reduce their effectiveness by enabling multi-factor authentication (MFA) across your organization. With MFA enabled, hackers will hit a wall without the secondary verification method even if they crack the initial password.
Additionally, you can disable various legacy protocols like SMB, Telnet, or POP3. Such protocols are often enabled by default but rarely needed in modern business environments. If not disabled, they provide attackers with additional entry points they can attempt to exploit.
2. Unusual Network Traffic Patterns
Your network traffic should follow predictable patterns based on your business operations. When you spot connections to unusual IP addresses—particularly from countries known for cybercriminal activity like Russia or North Korea—it’s time to investigate because they could indicate that your systems are communicating with command and control servers operated by hackers.
Similarly, sudden spikes in outbound traffic could mean that attackers are exfiltrating your sensitive data, especially if they happen during off-hours. That said, more capable and experienced attackers try to blend in with normal traffic patterns, so your best bet is to invest in a sophisticated network monitoring solution that leverages artificial intelligence to continuously analyze large volumes of network data in real time and identify even subtle anomalies.
3. Strange Processes Running on Your Servers/Devices
If you notice unfamiliar processes running on your servers or devices, it’s a major red flag that something isn’t right. Hackers often deploy malicious software to gain control of systems, extract data, or create backdoors for future access. In some cases, malicious processes are fairly easy to spot because they:
- Have random or gibberish names
- Consume unusually high CPU or memory resources
- Attempt to make network connections
However, malicious processes can also be much less obvious. Fileless malware, for example, hides within legitimate system processes like PowerShell or Windows Management Instrumentation (WMI), so it’s virtually impossible to detect through casual observation. That’s why it’s important to have advanced endpoint detection and response (EDR) solutions that can monitor process behavior and identify suspicious activities—even when they’re coming from seemingly legitimate system processes.
4. Changes to Security or Account Settings
When hackers gain access to your systems, they often modify security settings to maintain their foothold and make future access easier. These changes could include disabling security tools and logging features or modifying authentication requirements and password policies. Hackers may also create new privileged accounts or escalate privileges for existing ones.
Proper configuration and change management is your first line of defense against these threats. Implementing a structured process for tracking, approving, and documenting all changes makes it much easier to quickly flag for investigation any unexpected modifications.
5. Files Becoming Encrypted and Inaccessible
When your files suddenly become encrypted, and you discover ransom notes demanding payment in exchange for decryption keys, you’re dealing with criminals who’ve turned your data into hostages using ransomware, a type of malware that uses encryption for nefarious purposes.
Ransomware has become increasingly prevalent and costly. According to Sophos’s State of Ransomware 2024 report, 59% of organizations were hit by it in the past year, with 70% of attacks successfully encrypting data. What’s even more concerning is that ransom demands have increased five-fold in just the last 12 months.
To protect your organization against this dangerous threat, implement a multi-layered defense strategy:
- Maintain secure, tested backups that are kept out of attackers’ reach (ransomware can quickly spread across the network).
- Keep all systems patched and up to date (as 32% of ransomware attacks exploit unpatched vulnerabilities).
- Deploy advanced endpoint protection with anti-ransomware capabilities.
- Train your employees to recognize the phishing emails and social engineering tactics that often serve as ransomware’s initial entry point.
- Have an incident response plan ready because every minute counts when ransomware strikes.
With these defense measures in place, your organization can significantly reduce the risk of falling victim to ransomware and minimize the impact if an attack does occur.
6. Sudden System Crashes or Slowdowns
When your systems suddenly start crashing or running at a snail’s pace, it’s easy to blame routine IT issues. After all, these symptoms can have many innocent explanations—from Windows updates gone wrong to configuration changes or newly installed software. But if you haven’t made any significant changes to your environment yet performance problems persist, hackers and their malware might be to blame.
To prevent this from happening, you should prioritize the defense strategies outlined earlier in this article. However, it’s also paramount to have an automated desktop and server deployment process in place so that you can restore compromised systems to a known good state efficiently. This is where tools like Microsoft Deployment Toolkit (MDT) come into play, enabling IT teams to deploy customized Windows images with all required applications installed automatically.
7. Unauthorized Financial Activity
Sometimes, the most obvious sign that your organization has been hacked isn’t found in system logs or security alerts—it appears on your financial statements. Unexpected transactions, missing funds, or unusual transfer patterns could indicate that cybercriminals have compromised your financial accounts or successfully tricked your employees into sending them money.
Business Email Compromise (BEC) scams are a prime example of this threat. In these attacks, cybercriminals impersonate executives or trusted business partners via email to convince employees to initiate fraudulent wire transfers. While it may seem obvious in hindsight, these scams can be remarkably sophisticated, often using carefully researched details about your organization, its partners, and ongoing projects to make their requests appear legitimate.
While robust spam filtering and email security tools can help block many fraudulent messages, BEC and other social engineering attacks targeting your finance team can’t be stopped by technology alone. Your best defense is comprehensive security awareness training that teaches employees to verify unexpected payment requests through a different communication channel.
Conclusion
While the warning signs we’ve discussed can help you spot potential compromises, the reality is that modern cyber threats are becoming increasingly sophisticated and harder to detect without specialized expertise and tools. That’s where OSIbeyond’s Managed Security Services come in.
Our Security Operations Center (SOC) is staffed with a team of experts who leverage advanced Security Information and Event Management (SIEM) technology to provide continuous monitoring of your entire IT environment 24/7, giving you peace of mind and allowing you to focus on running your business.
Don’t wait until it’s too late—schedule a meeting with OSIbeyond today so that we can help you respond to cybersecurity incidents while there’s still plenty of time to mitigate damage.