INTERNET STORM CENTER SPOTLIGHT
ISC provides a free analysis and warning service to thousands of Internet users and organizations, and is actively working with Internet Service Providers to fight back against the most malicious attackers. https://isc.sans.edu/about.html
Njrat Campaign Using Microsoft Dev Tunnels
Published: 2025-02-27
Last Updated: 2025-02-27 08:54:32 UTC
by Xavier Mertens (Version: 1)
I spotted new Njrat samples that (ab)use the Microsoft dev tunnels service to connect to their C2 servers. This is a service that allows developers to expose local services to the Internet securely for testing, debugging, and collaboration. It provides temporary, public, or private URLs that will enable remote access to a development environment without deploying code to production. Dev tunnels create a secure, temporary URL that maps to a local service running on your machine, they work across firewalls and NAT, and their access can be restricted. This is a service similar to the good old ngrok.
Here are two samples ...
They use different dev tunnel URLs but their ImpHash (Import Hash) is the same ...
This is the code where the malware will send its status to the C2 server ...
Read the full entry: https://isc.sans.edu/diary/Njrat+Campaign+Using+Microsoft+Dev+Tunnels/31724/
Mark of the Web: Some Technical Details
Published: 2025-03-03
Last Updated: 2025-03-03 10:29:03 UTC
by Didier Stevens (Version: 1)
The Mark of the Web (MoTW) is file metadata in Windows that marks a file that was obtained from an untrusted source.
When a file is downloaded from the Internet, browsers will not only write the file to disk, but also include metadata with the origin of the file. This also applies when an email attachment is saved to disk with Outlook.
This metadata (MoTW) is used by several applications to activate extra precautions when a file from an untrusted source is opened. For exampe, Microsoft Office will open a document downloaded from the Internet in Protected View (indicated by the yellow banner), SmartScreen will prompt you before a file is launched, ...
The metadata/MoTW is stored in an Alternate Data Stream on NTFS disks. The name of this ADS is Zone.Identifier.
You can view this with Notepad, for example. Say that you downloaded a file from the Internet called invoice.docx, then you can view the MoTW with this command ...
Read the full entry: https://isc.sans.edu/diary/Mark+of+the+Web+Some+Technical+Details/31732/
Romanian Distillery Scanning for SMTP Credentials
Published: 2025-03-04
Last Updated: 2025-03-04 15:53:21 UTC
by Johannes Ullrich (Version: 1)
Lately, attackers have gotten more creative and aggressive in trying to find various credential files on exposed web servers. Our "First Seen" page each day shows many new versions of scans for secrets files like ".env".
Yesterday, I noted a couple of requests that stuck out a bit ...
The same attacker scanned for variations ...
Read the full entry: https://isc.sans.edu/diary/Romanian+Distillery+Scanning+for+SMTP+Credentials/31736/