CVE-2017-20203

NetSarang v5.0 Malicious Backdoor Supply Chain Compromise

Published Oct 9, 2025 CVSS 4.0 · 9.3 Critical EPSS < 1% KEV · Not listed
Description
NetSarang Xmanager Enterprise 5.0 Build 1232, Xmanager 5.0 Build 1045, Xshell 5.0 Build 1322, Xftp 5.0 Build 1218, and Xlpd 5.0 Build 1220 contain a malicious nssock2.dll that implements a multi-stage, DNS-based backdoor. The dormant library contacts a C2 DNS server via a specially crafted TXT record for a month‑generated domain. After receiving a decryption key, it then downloads and executes arbitrary code, creates an encrypted virtual file system (VFS) in the registry, and grants the attacker full remote code execution, data exfiltration, and persistence. NetSarang released builds for each product line that remediated the compromise: Xmanager Enterprise Build 1236, Xmanager Build 1049, Xshell Build 1326, Xftp Build 1222, and Xlpd Build 1224. Kaspersky Lab identified an instance of exploitation in the wild in August 2017.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
CPEs cpe:2.3:a:netsarang:xftp:5.0:*:*:*:*:*:*:*
cpe:2.3:a:netsarang:xlpd:5.0.1220:*:*:*:*:*:*:*
cpe:2.3:a:netsarang:xmanager:5.0:*:*:*:*:*:*:*
cpe:2.3:a:netsarang:xshell:5.0:*:*:*:*:*:*:*
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Netsarang
Netsarang xftp
Netsarang xlpd
Netsarang xmanager
Netsarang xmanager Enterprise
Netsarang xshell
Vendors & Products Netsarang
Netsarang xftp
Netsarang xlpd
Netsarang xmanager
Netsarang xmanager Enterprise
Netsarang xshell
Type Values Removed Values Added
Description NetSarang Xmanager Enterprise 5.0 Build 1232, Xmanager 5.0 Build 1045, Xshell 5.0 Build 1322, Xftp 5.0 Build 1218, and Xlpd 5.0 Build 1220 contain a malicious nssock2.dll that implements a multi-stage, DNS-based backdoor. The dormant library contacts a C2 DNS server via a specially crafted TXT record for a month‑generated domain. After receiving a decryption key, it then downloads and executes arbitrary code, creates an encrypted virtual file system (VFS) in the registry, and grants the attacker full remote code execution, data exfiltration, and persistence. NetSarang released builds for each product line that remediated the compromise: Xmanager Enterprise Build 1236, Xmanager Build 1049, Xshell Build 1326, Xftp Build 1222, and Xlpd Build 1224. Kaspersky Lab identified an instance of exploitation in the wild in August 2017.
Title NetSarang v5.0 Malicious Backdoor Supply Chain Compromise
Weaknesses CWE-506
References
Metrics cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Nov 21, 2025, 2:17 PM
Reserved
Oct 8, 2025, 7:40 PM
Status
Deferred
Published
Oct 9, 2025, 5:15 PM
Modified
Jun 17, 2026, 1:15 AM