Oct 30 2022

Know the dangers you’re facing: 4 notable TTPs used by cybercriminals worldwide

Category: Attack MatrixDISC @ 5:22 pm

In this Help Net Security video, Dmitry Bestuzhev, Most Distinguished Threat Researcher at BlackBerry, talks about some of the most interesting tactics, techniques, and procedures employed by cybercriminals in recent months.

These are:

  1. The exploitation of Log4Shell
  2. Trojanization of security and privacy-focused tools
  3. Malicious ads based on the victim’s location and browser referrer
  4. Supply-chain attacks through open-source projects

Tags: Log4shell, Trojanization, TTPS

Mar 21 2022

Qualys platform study: Log4Shell, the menace continues

Category: Log4jDISC @ 9:32 pm

The anatomy of Log4Shell

By now, we are all familiar with the fact that Log4Shell is just about as critical as a critical vulnerability can get – scoring a 10 out of 10 on the National Institute of Standards and Technology’s CVSS severity scale.

As it targets a library – Apache Log4j2 – that nearly every Java application uses to log requests, this vulnerability is ubiquitous. Many applications use Log4j2 without even realizing it, meaning that even those with no apparent dependency on Log4j2 can still be at risk.

With its massive impact across nearly every industry, Log4Shell has taken its place in the cybersecurity hall of fame – among the likes of HeartBleed, WannaCry and ShellShock.

Difficult to locate but easy to exploit, remediating this vulnerability would prove incredibly complex, with several detection methods required. In fact, three months into Log4Shell, the Qualys Cloud Platform suggests that 30% of the Log4j instances still remain unpatched.

Qualys research team reveals the current state of Log4Shell

When it came to tracking the impact of Log4Shell, Qualys occupies a unique vantage point. The Qualys Cloud Platform indexes more than 10 trillion data points across its installed enterprise customer base and completed 6 billion IP scans per year with 75 million cloud agents deployed in hybrid IT environments globally. With that kind of scale, the Qualys Research Team was able to uncover unique insights into how global enterprises have and are managing Log4Shell:

Log4Shell exposure
  • Qualys Cloud Platform scanned more than 150 million IT assets, across all geographies, flagging 22 million vulnerable app installations. Of these, more than 80% were open source applications.
  • Log4Shell was detected in more than 3 million vulnerable instances.
  • More than two months later, 30% of Log4j instances remain unpatched.
Log4Shell threat landscape
  • Nearly 68,000 vulnerabilities were found in cloud workloads and containers across the U.S. and EMEA, reinforcing the recommendation that enterprises need to monitor running containers for flaws like Log4Shell.
  • CISA and NCSC reported 1,495 products vulnerable to Log4Shell, and of those we observed 1,065 products across 52 publishers currently in use. This indexing proved very valuable to Qualys customers as this SBOM mapping is provided out of the box, providing immediate insights into their vulnerable software inventory.
  • Surprisingly, more than 50% of application installations with Log4j were flagged as “end-of-support.” This means that these publishers will likely NOT be providing Log4Shell security patches for these apps.
  • The vulnerability was detected in more than 2,800 web applications. Since web apps are publicly facing, this was the first line of defense for many enterprises looking to fend off early attacks. In the U.S., most detections occurred before/during the holiday period, while in the E.U. these spiked after the holidays.
Vulnerability trends
  • The vast majority of the vulnerable assets (over 80%) were on Linux.
  • A total of 98 distinct Log4j versions were observed in use, 55% of which were vulnerable versions.
  • There was a 20% spike in detections as the new year arrived and employees returned to work.
  • Within the first month after Log4Shell’s disclosure, we observed that 12% of total Log4j installations were vulnerable, while only 5% were not.
Remediation trends
  • Average time to remediation after detection was 17 days. Systems which could be exploited remotely were patched faster (12 days) while internal systems were slower.
  • After the first month, remediation efforts plateaued and began trending down, quite likely because security teams are finding it easier to mitigate Log4Shell rather than permanently fixing it.
Attack patterns
  • Our Multi-Vector EDR solution detected 22,000 potential attacks per week at the height of the crisis. Many of these were scattershot “spray & pray” attacks trying to infect as many systems as possible quickly. Our data indicates that threat actors were trying to take advantage of the holiday season window of opportunity.
  • Attacks also trended down into January, as mitigating controls and patches were rolled out by enterprise IT teams.

Unpacking Log4Shell’s continued peril

Log4j has been and will continue to be a headache for security professionals due to how difficult it is to fully understand where this vulnerability may be within an organization.

As with most vulnerabilities, understanding how and where the flaw will affect your business is crucial. Discovery processes are unique to each organization – meaning that depending on architecture and deployment, timetables vary.

This paired with obstacles such as the complexities of skeleton IT staff, potential lack of visibility into IT assets and an overall influx of other real-time sophisticated attacks and threats, could present a tumultuous road to immediate remediation.

Why are vulnerable Log4j versions continuing to be downloaded?

The main culprit for why vulnerable versions continue to be downloaded is likely because of automated build systems. These are configured to download a specific version build of their dependencies. Lesser maintained projects may automatically download a specific version to avoid conflicts with updated software, which has the potential to break their code. If the maintainer of that software hasn’t been paying attention to Log4j news their application is left open to the risk of exploitation.

Another scenario is the intentional download by researchers or adversaries to test exploitation of their latest wares. It is useful for both good and bad guys to continually validate that their exploitations or defenses are in working order outside of production areas.

Why are vulnerable Log4j versions still available for download?

Flawed forms of the code are still available because many other pieces of software still rely on them. Removing these downloads could potentially cause breakage in several systems if eliminated.

Further, The Qualys Research team found that more than 50% of application installations with Log4j were flagged as “end of support.” These publishers will likely not be providing Log4Shell security patches for these apps. End of life/support technology is one of the leading factors that put organizations at risk of being exploited by threat actors.

In fact, earlier this year, CISA developed a catalog of “Bad Practices” to showcase what is exceptionally risky. Landing at number one – especially for organizations supporting Critical Infrastructure or NCFs – was the use of unsupported software.

What’s next?


Log4Shell 2 Hours Hands-On Log4j Vulnerability

Tags: Log4shell, Log4Shell Log4j

Jan 11 2022

Night Sky ransomware operators exploit Log4Shell to target hack VMware Horizon servers

Category: Information Security,Log Management,Log4j,RansomwareDISC @ 10:40 am

The Night Sky ransomware operation started exploiting the Log4Shell flaw (

) in the Log4j library to gain access to VMware Horizon systems.

The ransomware gang started its operations on December 27, 2021, and has already hacked the corporate networks of two organizations from Bangladesh and Japan respectively. The gang has also set up a leak site on the Tor network where it will publish files stolen to the victims that will not pay the ransom.

Researchers from MalwareHunterteam first spotted the ransomware family, once encrypted a file, the ransomware appends the ‘.nightsky extension to encrypted file names.

In early January, threat actors started targeting VMware Horizon systems exposed on the Internet. VMware has addressed Log4Shell in Horizon with the release of 2111, 7.13.1, 7.10.3 versions, but unfortunately many unpatched systems are still exposed online.

On Monday, Microsoft posted a warning about a new campaign from a China-based actor it tracks as DEV-0401 to exploit the Log4Shell vulnerability on VMware Horizon systems exposed on the internet, and deploy Night Sky ransomware.

Tags: Log4shell, Night Sky ransomware

Jan 07 2022

Log4Shell-like security hole found in popular Java SQL database engine H2

Category: Log Management,Log4j,Security logsDISC @ 10:14 am

“It’s Log4Shell, Jim,” as Commander Spock never actually said, “But not as we know it.”

That’s the briefest summary we can come up with of the bug CVE-2021-42392, a security hole recently reported by researchers at software supply chain management company Jfrog.

This time, the bug isn’t in Apache’s beleagured Log4j toolkit, but can be found in a popular Java SQL server called the H2 Database Engine.

H2 isn’t like a traditional SQL system such as MySQL or Microsoft SQL server.

Although you can run H2 as a standalone server for other apps to connect into, its main claim to fame is its modest size and self-contained nature.

As a result, you can bundle the H2 SQL database code right into your own Java apps, and run your databases entirely in memory, with no need for separate server processes.

As with Log4j, of course, this means that you may have running instances of the H2 Database Engine code inside your organization without realizing it, if you use any apps or development components that themselves quietly include it.

JNDI back in the spotlight

I Survived Log4Shell 2021

Tags: Log4shell, SQL database engine H2

Dec 21 2021

More than 35,000 Java packages impacted by Log4j flaw, Google warns

Category: Log4j,Security logs,Security vulnerabilitiesDISC @ 11:12 am

The Google Open Source Team scanned the Maven Central Java package repository and found that 35,863 packages (8% of the total) were using versions of the Apache Log4j library vulnerable to Log4Shell exploit and to the CVE-2021-45046 RCE.

“More than 35,000 Java packages, amounting to over 8% of the Maven Central repository (the most significant Java package repository), have been impacted by the recently disclosed log4j vulnerabilities (12), with widespread fallout across the software industry.” reads the report published by Google. “As far as ecosystem impact goes, 8% is enormous.”

The Google experts used the Open Source Insights, a project used to determine open source dependencies, to assess all versions of all artifacts in the Maven Central Repository.

The experts pointed out that the direct dependencies account for around 7,000 of the affected packages. Most of the affected artifacts are related to indirect dependencies.


“The deeper the vulnerability is in a dependency chain, the more steps are required for it to be fixed. The following diagram shows a histogram of how deeply an affected log4j package (core or api) first appears in consumers dependency graphs.” reads the post published by the researchers. “For greater than 80% of the packages, the vulnerability is more than one level deep, with a majority affected five levels down (and some as many as nine levels down). These packages will require fixes throughout all parts of the tree, starting from the deepest dependencies first.”

But since the vulnerability was disclosed, 13% of all vulnerable packages have been fixed (4,620).

How long will it take for this vulnerability to be fixed across the entire ecosystem?

Log4j Java Programmer Programming Coding Funny Tote Bag

Tags: Java packages, Log4j, Log4shell

Dec 20 2021

Log4Shell: The Movie… a short, safe visual tour for work and home

Category: Log Management,Log4j,Security vulnerabilitiesDISC @ 11:52 am

As Christmas 2021 approaches, spare a thought for your sysamins, for your IT team, and for your cybersecurity staff.

There may be plenty of mice stirring all through the IT house right up to Christmas Eve…

…because that’s the deadline set by the US Cybersecurity and Infrastructure Security Agency (CISA) for patching the infamous Log4Shell vulnerability, a dangerously exploitable flaw in Apache’s widely used Log4j (Logging for Java) programming toolkit.

Since news first broke of the problem on 09 December 2021, Apache has a-patched the code not once but three times, variously fixing CVE-2021-44228 with version 2.15.0, quickly followed by 2.16.0 to fix a related bug dubbed CVE-2021-45046, foillowed quickly yet again by 2.17.0 to deal with CVE-2021-45105.

Why the pressure from CISA? Why the rush when we’re supposed to enjoying a global holiday season? Why not wait until New Year and deal with things then?

Here’s why your sysadmins are taking one (three, actually) for the team…

Log4Shell Response and Mitigation Recommendations

Advisory: 2021-007: Log4j vulnerability – advice and mitigations

Apache Log4j 2 v. 2.17.0 User’s Guide

Tags: Log4j, Log4shell

Dec 16 2021

While attackers begin exploiting a second Log4j flaw, a third one emerges

Category: App Security,Log4j,Security vulnerabilitiesDISC @ 9:54 am

Experts warn that threat actors are actively attempting to exploit a second bug disclosed in the popular Log4j logging library.

American web infrastructure and website security company Cloudflare warns that threat actors are actively attempting to exploit a second vulnerability, tracked as CVE-2021-45046, disclosed in the Log4j library.

The CVE-2021-45046 received a CVSS score of 3.7 and affects Log4j versions from 2.0-beta9 through 2.12.1 and 2.13.0 through 2.15.0 (which was released to fix CVE-2021-44228).

The Apache Software Foundation (ASF) has already released a patch for the Log4Shell vulnerability (CVE-2021-44228), but this fix partially address the flaw in certain non-default configurations. An attacker with control over Thread Context Map (MDC) input data when the logging configuration uses a non-default Pattern Layout with either a Context Lookup (for example, $${ctx:loginId}) or a Thread Context Map pattern (%X, %mdc, or %MDC) can craft malicious input data using a JNDI Lookup pattern triggering a denial of service (DOS) condition.

Both issues were assessed with the release of Log4j 2.16.0 version that addresses the CVE-2021-45046 by removing support for message lookup patterns and disabling JNDI functionality by default.

“Hot on the heels of CVE-2021-44228 a second Log4J CVE has been filed CVE-2021-45046. The rules that we previously released for CVE-2021-44228 give the same level of protection for this new CVE.” states CloudFlare.”This vulnerability is actively being exploited and anyone using Log4J should update to version 2.16.0 as soon as possible, even if you have previously updated to 2.15.0. The latest version can be found on the Log4J download page.”

The bad news are not ended, because researchers at security firm Praetorian warned of a third security vulnerability the Log4j version 2.15.0 that was released to fix the initial Log4Shell.

This third vulnerability can be exploited by attackers to exfiltrate sensitive data in certain circumstances.

“However, in our research we have demonstrated that 2.15.0 can still allow for exfiltration of sensitive data in certain circumstances. We have passed technical details of the issue to the Apache Foundation, but in the interim, we strongly recommend that customers upgrade to 2.16.0 as quickly as possible.” states the post published by Praetorian.

This image has an empty alt attribute; its file name is image-13.png

Secure By Design

Secure Software Development Fundamentals Professional Certificate

Tags: Log4j, Log4shell, Secure By Design

Dec 15 2021

Log4Shell: A new fix, details of active attacks, and risk mitigation recommendations

Category: Log4j,Security vulnerabilitiesDISC @ 1:22 pm

New versions of Log4j

The recent discovery of a second Log4j vulnerability (CVE-2021-45046) has shown that the fix to address CVE-2021-44228 in Apache Log4j 2.15.0 was incomplete in certain non-default configurations.

This vulnerability could allow attackers to craft malicious input data using a JNDI Lookup pattern, resulting in a denial of service (DoS) attack.

“Note that previous mitigations involving configuration such as to set the system property ‘log4j2.noFormatMsgLookup’ to ‘true’ do NOT mitigate this specific vulnerability,” the Apache Log4j security team noted.

“Log4j 2.16.0 fixes this issue by removing support for message lookup patterns and disabling JNDI functionality by default. This issue can be mitigated in prior releases (<2.16.0) by removing the JndiLookup class from the classpath (example: zip -q -d log4j-core-*.jar org/apache/logging/log4j/core/lookup/JndiLookup.class).” The team advises users either to upgrade to version 2.12.2 (for Java 7) or 2.16.0 (for Java 8 or later), in which the Message Lookups feature has been removed and access to JNDI has been disabled by default, and explained why some of the mitigation measures shared a few days ago are incomplete.

Active exploitation

PoCs are constantly popping up on GitHub and getting forked. GitHub is steadily working on removing them, but the proverbial cat is now out of the bag, and there is no going back.

Exploitation attempts detected so far in the wild can be tied to ransomware groups and access brokers, botnet herders (delivering coin miners), and nation-backed APTs.

“The way modern products are built is using a big hierarchy of dependencies, where developers use libraries written by third-party companies and engineers to speed up the software release process. Log4J is an extremely basic library that allows log writing in Java applications. The way CVE-2021-44228 affects comes in 3 layers – cloud products that directly use the Log4J, web applications that use libraries that use Log4J, and off-the-shelf software which is internally deployed on customer servers and endpoints,” says Michael Assraf, CEO at Vicarius.

“As fixing and deploying cloud applications can be fast, updating libraries that use Log4J can break functionality unless done with caution. The most problematic fixes are internally deployed software, which will have to wait for a vendor update or a security patch, in that scenario customers are advised to wait on further vendor guidance and as of right now are helpless in reacting. Examples include: Elasticsearch, Intellij IDE, Jira Confluence, Apache Tomcat, Minecraft, Apache Hadoop, Eclipse IDE, and many more.”

Gallagher says that the most immediate priority for defenders is to reduce exposure by patching and mitigating all corners of their infrastructure and investigate exposed and potentially compromised systems.

“Where systems have been identified as vulnerable, defenders should run an incident response process and monitor for signs of remote access trojans such as C2 call-backs. Secrets stored on exposed systems should also be rotated, particularly if they are exposed in environment variables. Lastly, consider critical third party vendors who may also be at risk,” he advised.

Mathew Eble, VP of Services at Praetorian, also warned the issue will be prone to false negatives.

“Externally there is no way to cover all the possible paths that exploitation can take. Even when external scanning tools get more sophisticated in how they identify the issue, we strongly advocate not relying on scan results as strong indicator of your risk,” he noted.

This recommendation is based on four issues the company has confirmed when working with customers. Based on this, they have expanded their initial recommendations for defenders.

Log4Shell mitigation

Secure By Design

Secure Software Development Fundamentals Professional Certificate

Tags: Log4j, Log4shell, Secure By Design

Dec 14 2021

Here We Go Again: Second Log4j Flaw Surfaces

Category: Log Management,Log4j,Security logsDISC @ 11:03 pm

Maybe Log4j vulnerabilities are like rats—for every one that’s visible, multiple others scurry beneath the surface. It’s too early to tell if that’s what will happen with Log4j.

But just a day or so after a damaging vulnerability was disclosed, another has come to light. This time it’s believed to be moderate in severity.

“A second vulnerability involving Apache Log4j was found on Tuesday,” according to a MITRE alert. “The description on the new CVE 2021-45046 said the fix to address CVE-2021-44228 in Apache Log4j 2.15.0 was ‘incomplete in certain non-default configurations.’”

“When a vulnerability is discovered and makes as much noise as Log4Shell, it invariably signals that there are additional vulnerabilities in the same software or fixes for that software and that triggers additional research and discovery,” said Casey Ellis, founder and CTO at Bugcrowd.

“The technique of abusing JNDI lookups with user-generated data has been around for years,” agreed Davis McCarthy, principal security researcher at Valtix. “With the attention CVE-2021-44228 has received, I wouldn’t be surprised if we saw a third CVE related to Log4j2.”

Ellis pointed out that “in this case, the initial fix provided was developed in a way that mitigated the exploitable symptom, but didn’t properly address the root cause.”

Indeed, Apache said the fix addressing “CVE-2021-44228 in Apache Log4j 2.15.0 was incomplete in certain non-default configurations,” according to the alert. “This could allow attackers with control over thread context map (MDC) input data when the logging configuration uses a non-default pattern layout with either a context lookup (for example, $${ctx:loginId}) or a thread context map pattern (%X, %mdc, or %MDC) to craft malicious input data using a JNDI lookup pattern resulting in a denial-of-service (DOS) attack.”

The alert said, “Log4j 2.15.0 restricts JNDI LDAP lookups to localhost by default.” But previous mitigations that involve “configuration such as to set the system property `log4j2.noFormatMsgLookup` to `true` do not mitigate this specific vulnerability,” MITRE warned. “Log4j 2.16.0 fixes this issue by removing support for message lookup patterns and disabling JNDI functionality by default. This issue can be mitigated in prior releases (<2.16.0) by removing the JndiLookup class from the classpath (example: zip -q -d log4j-core-*.jar org/apache/logging/log4j/core/lookup/JndiLookup.class).”

Ellis said the situation “also highlights the dangerous dependency open source users have on libraries which power large portions of the Internet but are ultimately written and maintained by unfunded volunteers with limited available time.” He gave credit to “ the Log4j maintainers” who he said likely “had an even busier and more stressful week than those in cybersecurity and are working on fixing and improving Log4j’s resilience as quickly as they can.”

Incomplete fixes are often a result of rushing patches to fix vulnerabilities, noted John Bambenek, principal threat hunter at Netenrich. The solution, he said, “is to disable JNDI functionality entirely (which is the default behavior in the latest version).”

Since “at least a dozen groups are using these vulnerabilities,” immediate action should then be taken “to either patch, remove JNDI or take it out of the classpath—preferably all of the above,” said Bambenek.

Manu Singh, risk engineer at Cowbell Cyber, sees an opportunity to show “a real-life use case where cyberinsurers can step up and help businesses.”

Singh said that Cowbell Cyber notified its policyholders of the vulnerabilities. “And our risk engineering team is available to help,” said Singh. “This is crucial in the small and mid-size market where security and IT resources are limited.”

Log4j Breach Discovery Takes 197 Days


CISA adds Log4Shell Log4j flaw to the Known Exploited Vulnerabilities Catalog

Tags: Log4j, Log4shell

Dec 13 2021

CISA adds Log4Shell Log4j flaw to the Known Exploited Vulnerabilities Catalog

Category: Log4j,Security vulnerabilities,Web SecurityDISC @ 9:53 am

CISA adds Log4Shell Log4j flaw to the Known Exploited Vulnerabilities Catalog

The U.S. CISA added 13 new vulnerabilities to the Known Exploited Vulnerabilities Catalog, including Apache Log4Shell Log4j and Fortinet FortiOS issues.

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) added 13 new vulnerabilities to the Known Exploited Vulnerabilities Catalog, including recently disclosed Apache Log4Shell Log4j and Fortinet FortiOS flaws.

Below is the list of new vulnerabilities added to the Known Exploited Vulnerabilities Catalog, which is the list of issues frequently used as attack vector by threat actors in the wild and that pose significant risk to the federal enterprise.

CVE NumberCVE TitleRemediation Due Date
CVE-2021-44228Apache Log4j2 Remote Code Execution Vulnerability12/24/2021
CVE-2021-44515Zoho Corp. Desktop Central Authentication Bypass Vulnerability12/24/2021
CVE-2021-44168Fortinet FortiOS Arbitrary File Download Vulnerability12/24/2021
CVE-2021-35394Realtek Jungle SDK Remote Code Execution Vulnerability12/24/2021
CVE-2020-8816Pi-Hole AdminLTE Remote Code Execution Vulnerability6/10/2022
CVE-2020-17463Fuel CMS SQL Injection Vulnerability6/10/2022
CVE-2019-7238Sonatype Nexus Repository Manager Incorrect Access Control Vulnerability6/10/2022
CVE-2019-13272Linux Kernel Improper Privilege Management Vulnerability6/10/2022
CVE-2019-10758MongoDB mongo-express Remote Code Execution Vulnerability6/10/2022
CVE-2019-0193Apache Solr DataImportHandler Code Injection Vulnerability6/10/2022
CVE-2017-17562Embedthis GoAhead Remote Code Execution Vulnerability6/10/2022
CVE-2017-12149Red Hat Jboss Application Server Remote Code Execution Vulnerability6/10/2022
CVE-2010-1871Red Hat Linux JBoss Seam 2 Remote Code Execution Vulnerability6/10/2022

The CVE-2021-44228 flaw made the headlines last week, after Chinese security researcher p0rz9 publicly disclosed a Proof-of-concept exploit for the critical remote code execution zero-day vulnerability (aka Log4Shell) that affects the Apache Log4j Java-based logging library.

The impact of the issue is devastating, thousands of organizations worldwide are potentially exposed to attacks and security experts are already reported exploitation attempts in the wild.

CISA also warns of a recently disclosed arbitrary file download vulnerability in FortiOS, tracked as CVE-2021-44168, that is actively exploited.

“A download of code without integrity check vulnerability [CWE-494] in the “execute restore src-vis” command of FortiOS may allow a local authenticated attacker to download arbitrary files on the device via specially crafted update packages.” reads the advisory published by Fortinet. “Fortinet is aware of an instance where this vulnerability was abused and recommends immediately validating your systems for indicators of compromise”

Log4Shell update: Attack surface, attacks in the wild, mitigation and remediation

Log4Shell explained – how it works, why you need to know, and how to fix it

Tags: CISA, Log4j, Log4shell

Dec 11 2021

Cybereason released Logout4Shell, a vaccine for Log4Shell Apache Log4j RCE

Category: Cyber Threats,Cyberweapons,Web SecurityDISC @ 12:48 pm

Chinese security researcher p0rz9 publicly disclosed a Proof-of-concept exploit for a critical remote code execution zero-day vulnerability, tracked a CVE-2021-44228 (aka Log4Shell), in the Apache Log4j Java-based logging library.

The Log4j is widely used by both enterprise apps and cloud services, including Apple iCloud and Steam.

A remote, unauthenticated attacker can exploit the CVE-2021-44228 to execute arbitrary code on a vulnerable system leading to a complete system takeover.

The vulnerability was discovered by researchers from Alibaba Cloud’s security team that notified the Apache Foundation on November 24. According to the experts, the vulnerability is easy to exploit and does not require special configuration, for this reason, it received a CVSSv3 score of 10/10. Researchers pointed out that Apache Struts2, Apache Solr, Apache Druid, Apache Flink are all affected by this vulnerability.

Now researchers from cybersecurity firm Cybereason have released a script that works as a “vaccine”(dubbed Logout4Shell) that allows remotely mitigating the Log4Shell vulnerability by turning off the “trustURLCodebase” setting in vulnerable instances of the library.

“While the best mitigation against this vulnerability is to patch log4j to 2.15.0 and above, in Log4j version (>=2.10) this behavior can be mitigated by setting system property log4j2.formatMsgNoLookups to true or by removing the JndiLookup class from the classpath. Additionally, if the server has Java runtimes >= 8u121, then by default, the settings com.sun.jndi.rmi.object.trustURLCodebase and com.sun.jndi.cosnaming.object.trustURLCodebase are set to “false”, mitigating this risk. However, enabling these system property requires access to the vulnerable servers as well as a restart.” reads the GitHub Page set up for the Log4Shell project.

Cyberreson experts pointed out that enabling these system property requires access to the vulnerable servers, and the servers have to be restarted. 

A zero-day exploit for Log4j Java library could have a tsunami impact on IT giants

Defensive Security Handbook: Best Practices for Securing Infrastructure

Tags: Apache patch, Defensive Security, Log4j, Log4shell