Credential Theft: How Attackers Get in Without Ransomware

Credential theft is the act of obtaining legitimate login details, typically usernames and passwords, through deception, malware, or exploitation, and using them to gain unauthorised access to systems or accounts. Unlike attacks that rely on exploiting software vulnerabilities, credential theft allows an attacker to enter through the front door using valid credentials. From the outside, the access looks entirely normal.

When ransomware strikes, there is usually a clear signal that something has gone wrong. Credential theft offers no such signal. An attacker with stolen login details can move through a network, access sensitive data, and establish persistence without triggering standard security alerts.

That is precisely why attackers favour this approach, as it is harder to detect and often more effective than attempting to breach perimeter defences directly.

According to the UK Government's Cyber Security Breaches Survey 2025, phishing remains the most prevalent attack type, experienced by 85% of businesses that suffered a breach or attack in the past year [1]. It is also the most common starting point for credential harvesting, but far from the only one:

• Phishing and Fake Login Pages: Employees are directed to fraudulent websites mimicking legitimate services, where their credentials are captured the moment they log in.
• Keyloggers and Malware: Malicious software records keystrokes in real time, capturing usernames and passwords without the user's knowledge.
• Password Spraying Attacks: Attackers try a small number of commonly used passwords across many accounts, avoiding lockouts while systematically testing for weak credentials.
• Credential Reuse from Previous Breaches: Login details exposed in one breach are tested against other services, exploiting the widespread habit of reusing passwords across accounts.

Here is where the risk becomes particularly significant. Once an attacker has obtained valid login credentials, they do not need to force their way through your defences. They simply log in. And because their activity resembles that of a legitimate user, standard perimeter controls such as firewalls and antivirus software offer little protection, as the attacker is already inside.

This is what makes credential harvesting so damaging over time. An attacker with persistent access can move laterally through a network, escalating privileges and mapping systems without raising immediate suspicion. They can identify where sensitive data is stored, monitor communications, and position themselves for further action, whether that is data exfiltration, financial fraud, or the eventual deployment of ransomware.

According to IBM's Cost of a Data Breach Report 2024, breaches involving stolen credentials take an average of 292 days to identify and contain, the longest of any attack vector studied [2]. Nearly ten months of undetected access is not an edge case. For many businesses, it is the reality they only discover after significant damage has already been done.

Account compromise detection depends on recognising behaviour that deviates from established patterns. That requires consistent visibility into how accounts are being used day to day, not just alerts when something has already gone wrong.

Unusual login behaviour is one of the clearest indicators: an account authenticating at 3am from an overseas IP address or logging in from two countries within an impossibly short window, warrants immediate investigation.

Password spraying attacks leave traces too, typically a pattern of failed login attempts spread across many accounts before a successful access event appears in the logs. Privilege escalation is another signal worth monitoring closely. When an account begins requesting access to systems it has no history of using, particularly administrative functions or sensitive data stores, it often indicates that credential theft has already occurred and an attacker is expanding their foothold.

No single control eliminates the risk of credential theft entirely, but the following measures, used together, substantially reduce both likelihood and impact:

• Implement Multi-Factor Authentication: Multi-factor authentication (MFA) ensures stolen credentials alone are not enough to gain access. Apply it consistently to email, remote access tools, and any system holding sensitive data.
• Enforce Strong Password Policies and Credential Hygiene: Prevent password reuse, enforce complexity requirements, and check existing passwords against known breach databases. Act on any matches promptly.
• Deploy Privileged Access Management: Privileged access management (PAM) governs who can reach the most sensitive systems and under what conditions, limiting the damage if standard credentials are ever compromised.
• Apply Least Privilege Principles: Every account should have access only to what its role requires. A smaller access footprint means less for an attacker to exploit.

Prevention reduces risk, but it does not eliminate it entirely. Credential-based intrusions can still occur even in well-defended environments, which is why continuous monitoring is an essential part of any credible security posture.

Identity and access monitoring involves tracking authentication events, login times, access patterns, and privilege use across all systems. Anomalies are flagged for review, and in a well-configured environment, alerts are generated automatically when behaviour falls outside expected parameters.

This is where multi-factor authentication data, access logs, and endpoint telemetry work together to give security teams the visibility they need. Logging best practices matter here, as logs should be centralised, tamper-resistant, and retained for a sufficient period to support forensic investigation if an incident does occur.

The role of managed detection and response (MDR) services and security operations centre (SOC) capabilities is increasingly important in this context. Identity-based attacks are growing in sophistication, and the volume of data that needs to be monitored consistently exceeds what most internal teams can manage alone. A 24/7 SOC with purpose-built tooling for credential-based intrusions provides the kind of sustained visibility that makes early detection possible.

When credential theft is confirmed or strongly suspected, the response needs to be swift and structured. IBM's Cost of a Data Breach Report 2024 found that stolen credentials were the most common initial attack vector in UK breaches, with an average total cost of £4.27 million per incident [3].

The priority is containing the compromised account by disabling access, revoking active sessions, and preventing re-authentication. Credential resets should then be applied to any accounts sharing the same passwords or accessed during the period of compromise.

An access review follows, establishing who accessed what and when. This is where identity-based attacks become complex to unpick, as the activity log shows legitimate-looking events throughout. Digital forensics is essential at this stage, establishing breach scope and preserving evidence for insurance claims or legal proceedings.

And that’s where we come in.

Solace Cyber provides specialist support for organisations dealing with the risks and consequences of credential-based compromise. Our team delivers continuous monitoring for account compromise, giving businesses sustained visibility over authentication events and identity-based threats.

Where stolen credentials have already been used to gain access, our incident response and digital forensics capabilities allow us to establish exactly what happened, contain the breach, and support recovery.

We also work with businesses to improve their underlying security posture, including the implementation of privileged access management controls and identity threat detection capabilities that reduce the conditions in which credential theft can succeed. With ISO 27001 accreditation, 24/7/365 availability, and a proven six-step incident response process, Solace Cyber offers the expertise and responsiveness that serious credential-based threats demand.

Remember that credential theft rarely announces itself, and by the time the evidence is visible, the damage is often already significant. The businesses that fare best are those that treat identity security as a continuous discipline rather than a periodic concern, investing in MFA, robust monitoring, and professional support before an incident forces their hand.

If you are concerned about your organisation's exposure to credential-based threats, Solace Cyber is ready to help. Call us on 01202 308818 or get in touch via our contact form to speak with a member of our team.

[1] GOV.UK, “According to the UK Government's Cyber Security Breaches Survey 2025, phishing remains the most prevalent attack type, experienced by 85% of businesses that suffered a breach or attack in the past year”: https://www.gov.uk/government/statistics/cyber-security-breaches-survey-2025/cyber-security-breaches-survey-2025

[2] SpyCloud, “According to IBM's Cost of a Data Breach Report 2024, breaches involving stolen credentials take an average of 292 days to identify and contain, the longest of any attack vector studied”: https://spycloud.com/blog/5-takeaways-from-ibms-cost-of-a-data-breach-report-2024/

[3] IBM, “IBM's Cost of a Data Breach Report 2024 found that stolen credentials were the most common initial attack vector in UK breaches, with an average total cost of £4.27 million per incident”: https://uk.newsroom.ibm.com/IBM-Report-Soaring-Data-Breach-Disruption-Drive-Costs-to-Record-Levels