CVE-2017-20203

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.

Is your site exposed to CVE-2017-20203?

Run a free security scan — no signup, results in seconds.

Weakness Type (CWE)

CWE-506 CWE-506

References

Other References

https://securelist.com/shadowpad-in-corporate-networks/81432/ https://usa.kaspersky.com/about/press-releases/shadowpad-attackers-hid-backdoor-in-software-used-by-hundreds-of-large-companies-worldwide https://web.archive.org/web/20181022035109/https://www.netsarang.com/news/security_exploit_in_july_18_2017_build.html https://www.vulncheck.com/advisories/netsarang-malicious-backdoor-supply-chain-compromise

Frequently Asked Questions

What is CVE-2017-20203? +

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.

How do I check if I'm vulnerable to CVE-2017-20203? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2018-25117

VestaCP commit a3f0fa1 (2018-05-31) up to commit ee03eff (2018-06-13) contain embedded malicious code that resulted in a supply-chain compromise. New …

CVE-2026-44484

PyTorch Lightning is a deep learning framework to pretrain and finetune AI models. Versions 2.6.2 and 2.6.2 have introduced functionality …

CVE-2026-46421

The SAP Cloud Application Programming Model is a tool for building enterprise-grade cloud applications, and cap-js/cds-dbs is the monorepo for …

CVE-2025-59038

Prebid.js is a free and open source library for publishers to quickly implement header bidding. NPM users of prebid 10.9.2 …

CVE-2025-59039

Prebid Universal Creative (PUC) is a JavaScript API to render multiple formats. Npm users of PUC 1.17.3 or PUC latest …

CVE-2025-59140

backlash parses collected strings with escapes. On 8 September 2025, the npm publishing account for backslash was taken over after …