CVE-2017-20203: NetSarang v5.0 Malicious Backdoor Supply Chain Compromise
- Is it exploited?
Reported, not confirmed by CISA. VulnCheck KEV lists it as exploited in the wild. CISA has not added it to its Known Exploited Vulnerabilities catalog as of .
VulnCheck KEV lists it since . It cites 4 public reports, the first from .
- How likely is exploitation in the next 30 days?
- 0.7%
EPSS score, percentile 51.8 of all scored records. A probability estimated by FIRST, not a report of exploitation.
- How severe?
- 9.3 Critical
CVSS v4.0 base score, given by the CNA
- What should I do?
CISA has set no required action, because the vulnerability is not in KEV.
- Which versions are affected?
Affected
- 5.0 Build 1232
- 5.0 Build 1045
- 5.0 Build 1322
- 5.0 Build 1218
- 5.0 Build 1220
Source: CISA KEV 2026.10.29, as of ; VulnCheck KEV, as of ; FIRST EPSS, as of ; CVE List, as of . About the data.
Description
NetSarang v5.0 Malicious Backdoor Supply Chain Compromise
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.
Source: CVE List, as of . About the data.
What to do
Advisories and patches
This summary is based on the CVE record as of . Check the vendor's advisory before you act: affected versions and fixes can change.
Affected products and versions
Versions by product, as listed in the CVE record (5 products)
| Status | Versions |
|---|---|
| Affected | 5.0 Build 1232 |
Versions not listed are: unaffected.
| Status | Versions |
|---|---|
| Affected | 5.0 Build 1045 |
Versions not listed are: unaffected.
| Status | Versions |
|---|---|
| Affected | 5.0 Build 1322 |
Versions not listed are: unaffected.
| Status | Versions |
|---|---|
| Affected | 5.0 Build 1218 |
Versions not listed are: unaffected.
| Status | Versions |
|---|---|
| Affected | 5.0 Build 1220 |
Versions not listed are: unaffected.
Source: CVE List, as of . About the data.
Weakness
CWE-506, 1 CAPEC
- CWE-506: Embedded Malicious Code
Attack patterns (CAPEC)
- CAPEC-186: Malicious Software Update
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| CVE record last updated |