vulnwire
9.3crit

CVE-2017-20203

NetSarang v5.0 Malicious Backdoor Supply Chain Compromise

Published 12 mo ago · modified 4 mo ago · JSON

CVSS
9.3
v4.0 · CNA
CISA KEV
No
not known exploited
EPSS
0.7%
percentile 52%
Public exploits
0
none known

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.

CISA SSVC assessment

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
12 mo ago

Exploit prediction (EPSS)

0.67% probability of exploitation in the next 30 days, higher than 52% of all scored CVEs.

CVSS scores

Assigned byVersionScoreVector
CNA4.09.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N
CNA4.09.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • NetSarang Computer, Inc. Xmanager Enterprise
  • NetSarang Computer, Inc. Xmanager
  • NetSarang Computer, Inc. Xshell
  • NetSarang Computer, Inc. Xftp
  • NetSarang Computer, Inc. Xlpd

Classification

Weakness

References

  • web.archive.org /web/20181022035109/https://www.netsarang.com/news/security_exploit_in_july_18_2017_build. · vendor-advisory, patch
  • usa.kaspersky.com /about/press-releases/shadowpad-attackers-hid-backdoor-in-software-used-by-hundreds-of-lar · technical-description
  • securelist.com /shadowpad-in-corporate-networks/81432/ · technical-description
  • vulncheck.com /advisories/netsarang-malicious-backdoor-supply-chain-compromise · third-party-advisory

Sources

vulnwire keeps one entry per vulnerability: the CVE id wins, then GHSA; records that alias each other are merged. Machine-readable: JSON.