Protect against Log4J without patching
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Protect against Log4J without patching
Learn More

UncategorizedK2 can protect against Log4J without patching | Zero Day Attacks


December 20, 2021 Alex Begun, Chief Revenue Officer
K2 can protect against Log4J without patching

What is Log4J? 

With the continuous coverage, it is pretty certain by now every 5th grader knows what Log4Shell is but just in case you missed the news, it is a recently discovered vulnerability in a ubiquitous Java logging framework LOG4J. The vulnerability has been given a CVSS Score of 10, making it the most serious of discovered flaws. 

VentureBeat is reporting that Log4J attacks have been attempted on 44% of corporate networks 

Log4J Vulnerability and Impact 

The diagram below provides an overview of how the Log4J vulnerability works (courtesy of Juniper Networks Threat Labs). 

Once attackers are able to exploit the Log4J vulnerability they can remotely inject code into services that use the library with system-level privileges. This allows attackers to send requests to any application on the server as well as retrieve information about the system itself or, in the worst-case scenario, get full control of the environment by sending a request like this one: 


With a version of this last request, the vulnerability is exploited and allows the hacked server to start a connection with the attacking host through JNDI. The resulting connection provides the attacker with several options to take control of the vulnerable server and extract valuable information such as accounts, passwords, or internal configuration.  

WAFs are ineffective as Log4Shell and Zero Day defenses 

Many organizations rely on Web Application Firewalls (WAFs) for application security, and protection against attacks on vulnerabilities.  Unfortunately, WAFs are a signature-based technology and can help only when signatures for attacks become available and polymorphic attacks such as Log4J easily bypass WAFs. Twitter is abuzz with such examples of these attacks. 

WAFs typically do not have the visibility to see out-of-band attack elements such those in Log4J as shown in this analysis (courtesy of Sophos Labs). 


The obvious fix is to detect the existence of vulnerable libraries and upgrade them to a minimum version of 2.17.0.  For vendor proprietary applications, IT teams need to obtain updated software directly from the vendor.  Additional guidance is on the CISA (Cybersecurity and Infrastructure Security Agency) government site 

In cases where upgrading is not feasible, protection against attacks is still available using Runtime Application Self Protection (RASP) solutions and is highly recommended to prevent attacks on vulnerable applications. 

In more recent developments, another vulnerability was discovered in the same library that can result in denial-of-service attacks and hence the recommendation to upgrade to a minimum of release 2.17.0 which includes the fix. 

Free tools 

There are now many free tools available to scan for Log4J. Here is one of available on Github. 

Important Resources

Apache Log4J Guide

CISA Log4J Guidance

K2 can detect and block Zero Day Attacks like Log4J 

K2 detects and blocks all attacks without the need for any signatures, and in attacks where signatures are not yet available, such as Log4J, when it was announced.   

In the example shown below, the K2 RASP deterministic engine detected, and blocked Log4J before the CVE was issued.   

Figure 1. K2 Security Platform detecting and blocking an attack on LOG4J2 without patching


Demo 1. K2 Security Platform detecting and blocking an attack on LOG4J2 without patching

Figure 2. K2 Security Platform detecting vulnerable libraries 

Demo 2. K2 Security Platform detecting vulnerable libraries 

How does K2 do it?   

K2 Security Platform uses runtime deterministic security to monitor the application and has a deep understanding of the application’s control flows, DNA and execution.  By validating the application’s control flows, deterministic security is based on the application itself, rather than relying on past attacks to determine a zero-day attack.  Deterministic security results in the detection of sophisticated zero-day attacks and protects from application from the risks listed in the OWASP Top Ten, including RCE, XSS and SQL Injection. 

Find out more about K2 today by requesting a demo, or get your free trial.



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K2 Cyber Security delivers the Next Generation Application Security Platform to secure web applications and container workloads against sophisticated attacks in OWASP Top 10 and provides exploitable vulnerability detection during pre-production. K2’s Platform is deployed on production servers for runtime protection of applications and on pen-testing/pre-production/QA servers for interactive application security testing to identify the location of the vulnerable code. K2’s solution generates almost no false positives, eliminates breaches due to zero-day attacks, detects attacks missed by traditional security tools like Web Application Firewalls and host based EDR, finds missed exploitable vulnerabilities and dramatically reduces security cost. K2 Cyber Security is headquartered in the USA and provides cyber security solutions globally.


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