Cisco AnyConnect Start Before Logon (SBL) local privilege escalation

vendor:

Cisco AnyConnect Secure Mobility Client

by:

@Pcchillin

7.8

CVSS

HIGH

Privilege Escalation

269

CWE

Product Name: Cisco AnyConnect Secure Mobility Client

Affected Version From: 4.3.04027 and earlier

Affected Version To: 4.3.4028

Patch Exists: YES

Related CWE: CVE-2017-3813

CPE: a:cisco:anyconnect_secure_mobility_client:4.3.04028

Metasploit: https://www.rapid7.com/db/vulnerabilities/cisco-anyconnect-cve-2017-3813/, https://www.rapid7.com/db/vulnerabilities/oracle_linux-cve-2015-3813/, https://www.rapid7.com/db/vulnerabilities/redhat_linux-cve-2015-3813/, https://www.rapid7.com/db/vulnerabilities/amazon_linux-cve-2015-3813/, https://www.rapid7.com/db/vulnerabilities/centos_linux-cve-2015-3813/

Other Scripts:

Platforms Tested: Windows 10

2017

Cisco AnyConnect Start Before Logon (SBL) local privilege escalation

The exploit allows an attacker to run CMD.EXE with system privileges by manipulating the Cisco AnyConnect application from the logon screen. It also allows running scripts from a USB flash drive.

Mitigation:

Upgrade to version 4.3.04029 or later.

Source

Exploit-DB raw data:

# 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