Vigil@nce - Apache Solr: external XML entity injection
June 2018 by Vigil@nce
This bulletin was written by Vigil@nce : https://vigilance.fr/offer
SYNTHESIS OF THE VULNERABILITY
An attacker can transmit malicious XML data to Apache Solr, in order to read a file, scan sites, or trigger a denial of service.
Impacted products: Debian.
Creation date: 25/04/2018.
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 Solr parser allows external entities.
An attacker can therefore transmit malicious XML data to Apache Solr, in order to read a file, scan sites, or trigger a denial of service.
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