Analysis of a JSE File (Kimsuky APT)

2026-02-03 Shubho57

https://medium.com/@shubhandrew/analysis-of-a-jse-file-kimsuky-apt-79588d103f73

Thumbnail for Analysis of a JSE File (Kimsuky APT)

The analyzed Kimsuky-linked JSE file acts as a multi-stage Windows script dropper that embeds a twice-base64-decoded PE executable and writes it to disk for execution. The script abuses Windows Script Host components including FileSystemObject, ADODB Stream, XML DOM base64 handling, and hidden PowerShell execution to decode, drop, and run payload files from locations such as ProgramData or temporary directories. Static analysis of the stage-two executable shows native Win32 code using WinHTTP APIs for HTTP or HTTPS beaconing, with no plaintext C2 visible, suggesting an encoded or dynamically assembled configuration. Reported behaviors also include self-path discovery, special-folder access, file deletion activity, and an assessment that the payload likely functions as an info-stealer loader. The excerpt ties the activity to Kimsuky and highlights common defensive concerns around script-host abuse, hidden PowerShell, and obfuscated loader configuration.

Indicators of Compromise

Type Value First Seen Last Seen
YARA KIMSUKY_Dropper_Archive 2026-02-03 2026-02-03
YARA KIMSUKY_NUKESPED_DLL_Payload 2026-02-03 2026-02-03
YARA KIMSUKY_NUKESPED_JSE_Loader 2026-02-03 2026-02-03
HASH 485a886acdf832cce3fb902483e30f6… 2026-02-03 2026-02-03
HASH c89af74145a6dd5d6ee0f8283ae9420… 2026-02-03 2026-02-03
HASH 81e384471fcfa6752cb81ca1b7b9ee4… 2026-02-03 2026-02-03
HASH 7d994b591c2d4fafeb3e71278229566e 2025-11-06 2026-02-03

Related Actors

Related Reports

« Back