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Cybersecurity researchers have discovered an entirely new attack vector that enables adversaries to exploit the Log4Shell vulnerability on servers locally by using a JavaScript WebSocket connection.

“This newly-discovered attack vector means that anyone with a vulnerable Log4j version on their machine or local private network can browse a website and potentially trigger the vulnerability,” Matthew Warner, CTO of Blumira, said. “At this point, there is no proof of active exploitation. This vector significantly expands the attack surface and can impact services even running as localhost which were not exposed to any network.”

WebSockets allow for two-way communications between a web browser (or other client application) and a server, unlike HTTP, which is unidirectional where the client sends the request and the server sends the response.

While the issue can be resolved by updating all local development and internet-facing environments to Log4j 2.16.0, Apache on Friday rolled out version 2.17.0, which remediates a denial-of-service (DoS) vulnerability tracked as CVE-2021-45105 (CVSS score: 7.5), making it the third Log 4j2 flaw to come to light after CVE-2021-45046 and CVE-2021-44228.

The complete list of flaws discovered to date in the logging framework after the original Log4Shell remote code execution bug was disclosed is as follows —

  • CVE-2021-44228 (CVSS score: 10.0) – A remote code execution vulnerability affecting Log4j versions from 2.0-beta9 to 2.14.1 (Fixed in version 2.15.0)
  • CVE-2021-45046 (CVSS score: 9.0) – An information leak and remote code execution vulnerability affecting Log4j versions from 2.0-beta9 to 2.15.0, excluding 2.12.2 (Fixed in version 2.16.0)
  • CVE-2021-45105 (CVSS score: 7.5) – A denial-of-service vulnerability affecting Log4j versions from 2.0-beta9 to 2.16.0 (Fixed in version 2.17.0)
  • CVE-2021-4104 (CVSS score: 8.1) – An untrusted deserialization flaw affecting Log4j version 1.2 (No fix available; Upgrade to version 2.17.0)

“We shouldn’t be surprised that additional vulnerabilities were discovered in Log4j given the additional specific focus on the library,” Jake Williams, CTO and co-founder of incident response firm BreachQuest, said. “Similar to Log4j, this summer the original PrintNightmare vulnerability disclosure led to the discovery of multiple additional distinct vulnerabilities. The discovery of additional vulnerabilities in Log4j shouldn’t cause concern about the security of log4j itself. If anything, Log4j is more secure because of the additional attention paid by researchers.”

The latest development comes as a number of threat actors have piled on the Log4j flaws to mount a variety of attacks, including ransomware infections involving the Russia-based Conti group and a new ransomware strain named Khonsari. What’s more, the Log4j remote code execution flaw has also opened the door to a third ransomware family known as TellYouThePass that’s being used in attacks against Windows and Linux devices, according to researchers from Sangfor and Curated Intel.

images from Hacker News