Vulnerabilities

A critical vulnerability in the open-source logging software Apache Log4j 2 is fueling a chaotic race in the cybersecurity world, with the Apache Software Foundation (ASF) issuing an emergency security update as bad actors searched for vulnerable servers.

Log4j 2, developed by the ASF, is a widely used Java package that enables logging in an array of  popular applications. The bug, tracked as CVE-2021-44228, is a zero-day vulnerability that allows unauthenticated remote code execution (RCE) that could give attacks control of the systems the software is running in.

The vulnerability – which has been dubbed Log4Shell – has been given a severity score of 10/10, the highest score possible. The Apache Foundation released an emergency patch as part of the 2.15.0 release of Log4j 2 that fixes the RCE vulnerability.

The software is used by both enterprise applications as well as cloud-based services, and the vulnerability could have wide effects on enterprises, according to security professionals. Log4Shell reportedly also can impact the default configurations of several Apache frameworks, such as Apache Struts2, Apache Druid and Apache Flink.

More info: https://www.bleepingcomputer.com/news/security/new-zero-day-exploit-for-log4j-java-library-is-an-enterprise-nightmare/

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Hello All. VMware has shipped updates to address two security vulnerabilities in vCenter Server and Cloud Foundation that could be abused by a remote attacker to gain access to sensitive information.

The more severe of the issues concerns an arbitrary file read vulnerability in the vSphere Web Client. Tracked as CVE-2021-21980, the bug has been rated 7.5 out of a maximum of 10 on the CVSS scoring system, and impacts vCenter Server versions 6.5 and 6.7.

“A malicious actor with network access to port 443 on vCenter Server may exploit this issue to gain access to sensitive information,” the company noted in an advisory published on November 23, crediting ch0wn of Orz lab for reporting the flaw.

The second shortcoming remediated by VMware relates to an SSRF (Server-Side Request Forgery) vulnerability in the Virtual storage area network (vSAN) Web Client plug-in that could allow a malicious actor with network access to port 443 on vCenter Server to exploit the flaw by accessing an internal service or a URL request outside of the server.

The company credited magiczero from SGLAB of Legendsec at Qi’anxin Group with discovering and reporting the flaw.

Further information can be found at:

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Hello All. I wanted to pass on these pretty good technical details on the vulnerabilities affecting Microsoft Exchange on-premise:

After exploiting these vulnerabilities to gain initial access, HAFNIUM operators deployed web shells on the compromised server. Web shells potentially allow attackers to steal data and perform additional malicious actions that lead to further compromise. One example of a web shell deployed by HAFNIUM, written in ASP, is below:

Following web shell deployment, HAFNIUM operators performed the following post-exploitation activity:

  • Using Procdump to dump the LSASS process memory:

  • Using 7-Zip to compress stolen data into ZIP files for exfiltration:

  • Adding and using Exchange PowerShell snap-ins to export mailbox data:

  • Using the Nishang Invoke-PowerShellTcpOneLine reverse shell:

  • Downloading PowerCat from GitHub, then using it to open a connection to a remote server:

HAFNIUM operators were also able to download the Exchange offline address book from compromised systems, which contains information about an organization and its users.

Our blog, Defending Exchange servers under attack, offers advice for improving defenses against Exchange server compromise. Customers can also find additional guidance about web shell attacks in our blog Web shell attacks continue to rise.

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