[UNIX] KisMAC Local Privilege Escalation
From: SecuriTeam (support_at_securiteam.com)
Date: 09/07/03
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To: list@securiteam.com Date: 7 Sep 2003 18:23:46 +0200
The following security advisory is sent to the securiteam mailing list, and can be found at the SecuriTeam web site: http://www.securiteam.com
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KisMAC Local Privilege Escalation
------------------------------------------------------------------------
SUMMARY
KisMAC is a popular wireless network identification and analysis tool. In
the event that the "SUID Shell Scripts are enabled" checkbox (inside of
the driver tab under preferences) is enabled, an attacker with local
interactive access can become root through several different mechanisms.
This feature is off by default.
DETAILS
@stake has identified five potential vulnerabilities within the setuid
shell scripts enabled by KisMAC. The core issue is that an attacker can
cause these shell scripts to use an attacker-controlled directory instead
of a system directory by hardlinking to any of the vulnerable shell
scripts. This happens during the execution of dirname(1).
viha_driver.sh / macjack_load.sh / airojack_load.sh
1) Change the ownership of user controlled files. Since we can change the
value of $DRIVER_KEXT, we can cause the chown command within the
load_driver function to change the ownership of a file/directory of our
choosing. An attacker can create a setuid executable owned by the
attacker's uid, that will get chown()'d to root. While the example used is
the viha_driver.sh script, both macjack_load.sh and airojack_load.sh can
also be used.
2) Load arbitrary kernel modules. The line underneath the chown show the
loading of the kernel extension located in $DRIVER_KEXT. Since we can
control this value, we can cause arbitrary kernel modules of our choosing
to be loaded into memory. While the example used is the viha_driver.sh
script, the macjack_load.sh and airojack_load.sh scripts can also be used.
exchangeKernel.sh
3) Install arbitrary kernel. Using similar techniques outlined above, an
attacker can overwrite the kernel with a kernel of their choosing.
setuid_enable.sh / setuid_disable.sh
4) Change the ownership of user controlled files. Both setuid_enable.sh
and setuid_diable.sh script are vulnerable to the attack outlined in
vulnerability #1. Additionally, setuid_enable.sh will actually add the
setuid bit to user controlled files after chown()ing the files to root.
viha_prep.sh / viha_unprep.sh
5) Execution of attacker controlled binary. Using a technique similar to
vulnerability #1, an attacker can cause an executable of their choosing to
be executed as root.
Vendor Response:
Upgrade to 0.05d4 at:
<http://www.binaervarianz.de/projekte/programmieren/kismac/download.php>
http://www.binaervarianz.de/projekte/programmieren/kismac/download.php.
Recommendation:
Do not enable this functionality on a multi-user machine. If this is a
requirement, only allow users with in the admin group access to the setuid
shell scripts.
ADDITIONAL INFORMATION
The original advisory can be downloaded from:
<http://www.atstake.com/research/advisories/2003/a082203-1.txt>
http://www.atstake.com/research/advisories/2003/a082203-1.txt.
The information has been provided by <mailto:daveg@atstake.com> Dave G.
of @Stake.
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