Security Information and Event Management (SIEM) systems serve as the primary tool for detecting suspicious activity in enterprise networks and helping organizations identify and respond to potential attacks in real time. However, the new Picus Blue Report 2025, based on over 160 million real-world attack simulations, reveals that organizations are detecting only one of seven simulated attacks, indicating a key gap between threat detection and response.
While many organizations believe they are doing everything they can to detect enemy actions, the reality is that many threats are sliding down unnoticed. This detection gap creates a false sense of security when attackers are already accessing sensitive systems, escalating privileges, or actively excluding valuable data.
Which raises the question: Why are these systems still failing, money, attention? Especially when the interests are very high. Let’s take a look at what Blue Report 2025 has taught us about some lingering core issues regarding the effectiveness of SIEM rules.
Log Collection Faults: Detected Fault Fundamentals
SIEM rules act like security guards who monitor incoming and outgoing traffic for suspicious behavior. SIEM rules are pre-configured to detect certain activities, such as unauthorized access and anomalous network traffic, so that security guards follow a set of instructions to identify threats based on a particular pattern. When a particular event matches a rule, an alert is triggered, allowing security teams to respond quickly.
However, for SIEM rules to work effectively, you need to analyze a comprehensive set of trustworthy logs. Blue Report 2025 discovered that one of the most common reasons why SIEM rules fail is due to persistent issues with log collections. In fact, in 2025, 50% of detection rule failures were linked to log collection issues. If the logs are not captured properly, it is very easy to miss important events, leading to a lack of dangerous alerts, false sense of security, and a failure to detect malicious activity. Even the most effective rules quickly become useless without analyzing accurate data, making organizations vulnerable to attacks.
Common log collection issues include missed log sources, misunderstood log agents, and incorrect log configurations. For example, many environments do not have problems recording key data points or log forwarding, preventing the associated log from reaching SIEM first. Failure to capture this critical telemetry significantly impedes SIEM’s ability to detect attacker malicious activity.
Misunderstood detection rules: silent failure
Even if the logs are collected properly, detection rules can fail due to incorrect collection. In fact, in 2025, 13% of rule obstacles were attributed to configuration issues. This includes incorrect rule thresholds, inappropriately defined sets of references, and inadequately constructed correlation logic. These issues can undermine the effectiveness of your SIEM system by missing important events or causing false positives.
For example, excessively widespread or general rules can lead to overwhelming amounts of noise. This often leads to important alerts that are buried in a signal, completely missed, or accidentally ignored. Similarly, undefined sets of references can cause the rules to miss key indicators of compromise.
Performance Issues: Hidden Criminals of Detection Gap
Performance issues can quickly become another major hurdle as SIEM systems scale to process more data. The report found that 24% of detection failures in 2025 were related to performance issues, including resource-rich rules, extensive custom property definitions, and inefficient queries. These issues can significantly slow detection times and delay response times, making it difficult for security teams to act quickly when they are actively under attack.
SIEM systems struggle to process large amounts of data, especially when rules are not optimized for efficiency. This slows down query performance, delays alerts, overwhelm system resources, and further reduces the organization’s ability to detect real-time threats.
Three general detection rules issues
Let’s take a closer look at the three most common log collection issues highlighted in Blue Report 2025.
One of the most important issues affecting the effectiveness of SIEM rules is the consolidation of log sources. This occurs when event coalescence is enabled for certain log sources such as DNS, proxy servers, and Windows event logs, leading to data loss. In this case, important events can be compressed or discarded, resulting in incomplete data for analysis. As a result, critical threat behaviors can be easily missed, and detection rules can be ineffective immediately.
Another common problem is the unavailable log source, which accounts for 10% of the rule’s failures. This often occurs when logs are unable to send data due to network corruption, misunderstood log transfer agents, or firewall blocks. Without these logs, the SIEM system cannot capture critical events, resulting in detection rules not being able to trigger alerts.
Finally, delaying the implementation of cost-effective test filters is a common cause of detection failures. If detection rules are too broad or inefficient, the system will process excessive amounts of data without effective filtering. This will overwhelm your system, slow performance, and keep your security team from losing important events. According to the report, 8% of detection failures are related to this issue, highlighting the need for optimized, cost-effective filtering.
Continuous verification: Ensuring that SIEM rules are effective against evolving threats
Although detection rules are the basis of SIEM systems, they can quickly lose their relevance without continuous verification. Enemies are constantly evolving tactics, techniques, and procedures (TTP), and SIEM rules designed to detect known patterns are ineffective if they are not regularly tested against real-world threats.
Blue Report 2025 highlights that without continuous testing, even well-tuned SIEM systems can easily become vulnerable to attacks. Continuous verification not only relies on static configurations, but also regularly proves that detection is working for modern adversarial behavior. This aggressive approach closes the gap between the theoretical protection provided by detection rules and the practical, real-world effectiveness required for evolving threats.
By simulating actual adversarial behavior, security teams can assess whether detection rules are countering modern attack technologies, ensure that they are properly tailored to a particular environment, and ensure that they identify malicious behavior in a timely manner.
Regular exposure verification via tools such as violations and attack simulations allows organizations to constantly test and fine-tune controls. This approach makes it easier to identify blind spots and improve defenses, and SIEM rules can not only detect past attacks, but also prevent future attacks. Without continuous verification, organizations risk outdated or ineffective defenses from data, brand reputation and end results, putting their most important assets into unnecessary risk.
Close the SIEM detection gap
Ignored SIEM rules inevitably cannot detect modern threats. Log collection failures, false mining, and performance bottlenecks create blind spots, while static rules quickly lose their effect on evolving attacker tactics and techniques. Without continuous verification, organizations risk working under a false sense of security, putting critical systems and data at compromise.
To proceed, security teams need to periodically test and tune SIEM rules, simulate real attacks, and verify detection pipelines for the latest adversarial behavior. Tools such as violations and attack simulations allow organizations to uncover hidden gaps, prioritize high-risk exposures, and ensure that defenses are working when they are most important.
Check where Siem has succeeded and where it may quietly fail. Download Blue Report 2025 today for viable insights and recommendations for strengthening detection and prevention strategies for tomorrow’s attacks.
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