Top 6 Container Runtime Security Threats + 5 Defensive Measures

What Is Container Runtime Security? 

Container runtime security refers to measures and processes to protect containers while they are running in production environments. Unlike image scanning or static analysis, which focus on the build phase, runtime security identifies threats, vulnerabilities, and malicious activities when a container is live and interacting with other system components. This involves continuous monitoring, policy enforcement, and rapid response to any signs of compromise.

Runtime security also addresses the dynamic nature of containerized environments, where container instances are frequently created and destroyed. Traditional security tools for static or monolithic systems often fall short. Specialized solutions are required to ensure that ephemeral workloads and transient network connections in container ecosystems are adequately protected throughout their operational lifecycles.

This article is part of a series of articles about container security.

The Importance of Container Runtime Security 

During the runtime stage, containers are actively interacting with other system components, processing data, and providing services. This makes them prime targets for attackers seeking to exploit any weaknesses.

While container image scanning and secure orchestration are crucial during the build and ship stages, the runtime phase often receives less attention. However, security during runtime is critical, as containers share the host's kernel. If one container is compromised, the attacker could potentially escape the container's isolation and access other containers or even the host system, leading to severe security breaches.

Without strong runtime security measures, attackers could exploit vulnerabilities in the running containers, leading to data breaches, unauthorized access, or disruption of services. Hence, ensuring runtime protection is essential to protect the integrity, confidentiality, and availability of containerized applications and the underlying infrastructure.

Top Container Security Threats at Runtime 

1. Configuration Drift

Configuration drift occurs when the runtime state of a container diverges from its original intended configuration, often due to manual changes, automation glitches, or unauthorized access. This drift can open the door to security vulnerabilities that were not present at deployment, such as exposed ports, disabled security controls, or changed file permissions. 

If left unchecked, these discrepancies can be exploited by attackers seeking weak points within the running container environment. Organizations should use tooling that constantly monitors container states against known-good configurations and quickly notifies administrators of any deviations. 

2. Malicious Code

Malicious code refers to any unauthorized or harmful software introduced into a container during runtime. This can include web shells, rootkits, or scripts injected through compromised libraries or exploited vulnerabilities. 

Attackers often use malicious code to escalate privileges, establish persistent backdoors, or steal sensitive information from within running workloads. Preventing and detecting the execution of malicious code requires continuous observation of system processes, behavior profiling, and the application of allow-lists or block-lists at runtime. 

3. Malware in Container Images

Containers built from images can carry embedded malware that may not be detected during static analysis or scanning. During runtime, dormant malware within these images can activate, perform reconnaissance, or exfiltrate data. 

Attackers often hide sophisticated malware inside seemingly benign images hosted on public or private registries, making image provenance and runtime monitoring vital. Even with thorough image scanning before deployment, malware can evade detection through obfuscation or novel payloads that activate only under certain runtime conditions. 

4. Application Exploits

Application exploits target vulnerabilities within the containerized application itself—such as unpatched libraries, insecure input handling, or logic flaws—to execute unauthorized actions. Unlike infrastructure-level attacks, these exploits typically arise from bugs or misconfigurations in the application code that attackers can trigger during runtime.

Exploited applications may allow attackers to run arbitrary code, access sensitive data, or pivot to attack other services. Common vectors include SQL injection, remote code execution, and deserialization vulnerabilities. Because containers often encapsulate complex microservices, even small flaws in one component can compromise the integrity of the entire application.

Defending against application exploits requires a combination of secure coding practices, regular dependency updates, and runtime instrumentation. Runtime tools that observe application behavior can detect anomalies like unexpected process spawns, high-privilege file access, or unusual outbound connections—providing critical signals of in-progress exploitation.

5. Kernel Exploits

The Linux kernel, which underpins most container environments, presents a significant attack surface. Kernel exploits leverage vulnerabilities in the kernel to break out of container isolation and access the host. Attackers who succeed in exploiting the kernel can move laterally to compromise other containers, steal sensitive data, or take control of the entire host system. 

Proactively mitigating kernel exploits requires running containers with the least privileges necessary, keeping host operating systems and kernels up to date with patches, and employing runtime tools that monitor for suspicious system calls or behaviors indicative of exploit attempts. 

6. Exposure of Secrets

Secrets like API keys, passwords, and access tokens are often required by containers to function, but improper handling or exposure of these secrets represents a critical runtime threat. Secrets can be inadvertently logged, copied, or mounted inappropriately in containers, making them accessible to unauthorized users or attackers who gain access to the running workload.

To minimize exposure risks, organizations should utilize purpose-built secrets management solutions that inject secrets securely at runtime, avoid hard-coding credentials in images, and monitor containers for unauthorized access to sensitive files or environment variables. 

‍Related content: Read our guide to container vulnerability scanning (coming soon)

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Components of Container Runtime Security 

1. Behavioral Modeling and Anomaly Detection

Behavioral modeling and anomaly detection involve establishing a baseline of normal activity for containers and then continuously monitoring for deviations from this baseline. This is accomplished by collecting data about process execution, network traffic patterns, file accesses, and system calls. 

Machine learning and statistical techniques are often used to differentiate benign anomalies from truly suspicious behavior in large-scale environments. Effective behavioral modeling enables organizations to rapidly flag potential security incidents that might otherwise go unnoticed with signature-based approaches alone. 

For example, if a container suddenly initiates an outbound connection to an unfamiliar IP or spawns a process not seen during previous runs, these deviations trigger immediate scrutiny. 

2. Process and File Integrity Monitoring

Process and file integrity monitoring ensures that only authorized binaries and scripts are allowed to execute within a running container and that files are not tampered with during operation. This involves maintaining allow-lists or cryptographic fingerprints of trusted files and monitoring the execution tree for unrecognized or unauthorized processes. 

Any deviation from expected file or process states is promptly logged and flagged for investigation. By implementing continuous integrity checks, organizations can catch in-progress attacks that attempt to modify container workloads or insert malicious code post-deployment. 

This is especially important for sensitive directories such as /etc or application-specific paths where attackers may try to hide backdoors or persistence mechanisms. Alerting on unauthorized changes helps shorten response times and limit damage.

3. Network Traffic Analysis

Network traffic analysis at runtime involves examining both inbound and outbound data flows associated with running containers. This includes real-time inspection of protocols, ports, and communication endpoints to identify connections that deviate from expected patterns. 

Network segmentation, monitoring for lateral movement attempts, and detection of command-and-control activity are key focuses. Deploying runtime solutions that provide visibility into container network activity enables quick identification of indicators such as data exfiltration, unexpected peer communications, or network scans originating from compromised workloads. 

Enforced policies can restrict unauthorized communications and, combined with rapid alerting, help contain potential breaches before they escalate further.

4. Runtime Policy Enforcement

Runtime policy enforcement defines and applies security controls that govern what containers are permitted to do during their operation. These controls include restrictions on system calls, file system access, process spawning, and network communications, enforced using tools like KRSI, seccomp, AppArmor, and SELinux. 

Runtime policies are often specific to application requirements and tailored to minimize attack surfaces. Strong policy enforcement ensures containers operate within predefined boundaries, significantly reducing the likelihood of successful exploit attempts or privilege escalations. 

Automated policy management tools can dynamically adapt to changing workloads, automatically applying or updating restrictions as needed while minimizing the risk of false positives that could disrupt normal operations.

5. Intrusion Detection and Incident Response

Intrusion detection at the container runtime level focuses on identifying unauthorized access, code execution, or policy violations as soon as they occur. This typically integrates with centralized security operations and response processes, providing actionable alerts that allow security teams to contain or eradicate threats swiftly within running containers.

Effective incident response depends on having detailed, real-time telemetry from the container runtime, automated blocking or quarantining capabilities, and predefined playbooks for handling incidents. 

Post-breach analysis, forensic evidence collection, and lessons learned feed back into refining runtime security defenses, ensuring continuous improvement in threat detection and mitigation over time.

Essential Best Practices for Container Runtime Security

Here are some of the ways that organizations can ensure the security of their containers at runtime.

1. Restrict Privileges and Capabilities

Containers should be granted only the minimum level of access necessary to perform their tasks. For example, containers should not run with root privileges unless absolutely necessary. It’s crucial to configure containers to restrict their ability to interact with the host system or perform sensitive actions like loading kernel modules or accessing hardware directly.

Additionally, fine-tuning Linux capabilities—such as limiting raw socket access or restricting the ability to change file system permissions—ensures that containers are constrained to their role in the environment. This helps prevent an attacker who gains access to one container from escalating privileges or affecting other parts of the system. 

Securing system calls and enforcing these restrictions can also prevent malicious activity, such as privilege escalation or exploitation of vulnerabilities within the container.

2. Implement Resource Limits

To ensure containers operate within expected performance parameters, implementing resource limits is vital. By setting maximum limits for CPU, memory, disk I/O, and network bandwidth, organizations can prevent one container from monopolizing system resources. This improves stability and prevents compromised containers from disrupting the functioning of other containers or the host system.

For example, limiting memory usage ensures that a container cannot consume all available memory, leading to a denial-of-service condition for other services. Similarly, restricting CPU usage prevents any one container from taking too much processing power, which could slow down or halt other workloads. 

Resource limits are also an effective way to contain potential threats, such as resource exhaustion attacks, which could be used to slow down or destabilize the environment, providing an opportunity for attackers to exploit weaknesses or create persistent access.

3. Harden Container Images

Containers are built from images that may contain software, libraries, or configurations that introduce vulnerabilities. Ensuring these images are secure from the start is essential in preventing the deployment of compromised containers.

This begins with using minimal, trusted base images to reduce the attack surface by avoiding unnecessary components. Regular security scanning of these images for known vulnerabilities, misconfigurations, or hidden malware should be part of the image build process. In addition, images should be versioned and signed to ensure their integrity and verify their authenticity. 

Regularly updating images and incorporating security patches as part of the deployment lifecycle is necessary to address new vulnerabilities as they are discovered. It’s also important to avoid hard-coding sensitive information like credentials or API keys within images, as this creates a significant security risk.

4. Maintain a Trusted Container Registry

Organizations should establish secure policies for image storage and access, ensuring that only trusted personnel or automated processes can push new images into the registry. Access to container images should be tightly controlled, and only validated and secure images should be allowed to pass through the registry.

In addition, container images should be regularly audited for vulnerabilities and misconfigurations. Storing images in private, secured registries instead of public ones reduces the risk of exposure to potential attackers. 

Images should also be scanned for security issues at the time of upload, and any outdated or unpatched images should be flagged and either updated or removed. Establishing a process to track image versions ensures that only the latest, secure versions are deployed to production environments, minimizing the risk of using outdated or vulnerable container images.

5. Use Runtime Detection and Response

With continuous monitoring of container behavior, cloud application detection and response (CADR) solutions can detect abnormal activities in real time, such as suspicious system calls, unauthorized file access, or unusual network connections.  These solutions rely on behavior-based analysis to identify anomalies, comparing real-time activity against established baselines of normal container operations.

Once an anomaly is detected, the system can trigger automated responses, such as isolating the compromised container, revoking access to sensitive data, or terminating malicious processes. This rapid response reduces the window of opportunity for an attacker to escalate the breach or cause damage. 

In addition to detection, runtime response mechanisms should be integrated with incident management and alerting systems, enabling teams to act swiftly and efficiently in case of a security incident. Collecting detailed telemetry during runtime also supports forensic analysis, helping organizations understand the attack vector and improve future defenses. 

Container Runtime Security with Oligo

Oligo CADR provides robust container runtime security with a single agent per host infrastructure that minimizes impact to applications and infrastructure. Learn more about Oligo Cloud Application Detection & Response (CADR).