The Sophos UTM VPN endpoint interacts with client software provided by NPC Engineering (www.ncp-e.com). The affected client software, "Sophos IPSec Client" 11.04 is a rebranded version of NCP "Secure Entry Client" 10.11 r32792. A vulnerability in the software update feature of the VPN client allows a man-in-the-middle (MITM) or man-on-the-side (MOTS) attacker to execute arbitrary, malicious software on a target user's computer. This is related to SIC_V11.04-64.exe (Sophos), NCP_EntryCl_Windows_x86_1004_31799.exe (NCP), and ncpmon.exe (both Sophos and NCP). The vulnerability exists because: (1) the VPN client requests update metadata over an insecure HTTP connection; and (2) the client software does not check if the software update is signed before running it.

References

• https://nvd.nist.gov/vuln/detail/CVE-2017-17023
• https://www.ncp-e.com/en/resources/download-vpn-client/#c8680
• https://www.ncp-e.com/fileadmin/pdf/service_support/release_notes/NCP_Secure_Clients/NCP_Secure_Entry_Client/NCP_RN_Win_Secure_Entry_Client_11_14_r42039_en.pdf