The Vigil@nce team watches public vulnerabilities impacting your computers, and then offers security solutions, a vigilance database and tools to fix them.

Vulnerability of Apache Log4j: external XML entity injection

Synthesis of the vulnerability 

An attacker can transmit malicious XML data to Apache Log4j, in order to read a file, scan sites, or trigger a denial of service.
Impacted software: log4j.
Severity of this computer vulnerability: 2/4.
Creation date: 01/09/2017.
Références of this announce: VIGILANCE-VUL-23698.

Description of the vulnerability 

XML data can contain external entities (DTD):
  <!ENTITY name SYSTEM "file">
  <!ENTITY name SYSTEM "http://server/file">
A program which reads these XML data can replace these entities by data coming from the indicated file. When the program uses XML data coming from an untrusted source, this behavior leads to:
 - content disclosure from files of the server
 - private web site scan
 - a denial of service by opening a blocking file
This feature must be disabled to process XML data coming from an untrusted source.

However, the Apache Log4j parser allows external entities.

An attacker can therefore transmit malicious XML data to Apache Log4j, in order to read a file, scan sites, or trigger a denial of service.
Full bulletin, software filtering, emails, fixes, ... (Request your free trial)

This security announce impacts software or systems such as log4j.

Our Vigil@nce team determined that the severity of this threat is medium.

The trust level is of type confirmed by the editor, with an origin of document.

An attacker with a expert ability can exploit this computer vulnerability announce.

Solutions for this threat 

Apache Log4j: version 2.9.0.
The version 2.9.0 is fixed:
  https://logging.apache.org/log4j/

Apache JMeter: version 4.0.
The version 4.0 is fixed:
  http://jmeter.apache.org/download_jmeter.cgi
Full bulletin, software filtering, emails, fixes, ... (Request your free trial)

Computer vulnerabilities tracking service 

Vigil@nce provides a networks vulnerabilities alert. The Vigil@nce vulnerability database contains several thousand vulnerabilities.