Sunday, June 16, 2024

APT Hackers Abusing Microsoft Crypto API to Drop Backdoor on Windows Using Weaponized Shellcode

Researchers discovered a new wave of malware campaign that believed to be launched by APT hackers group using legitimate NSIS software to pack and launch the Shellcode on Windows.

NSIS (Nullsoft Scriptable Install System) is an open-source system script-driven installer authoring tool for Microsoft Windows and is used to create Windows installers.

Attackers abusing the Microsoft Crypto API to decrypt the final payload from the packer named “Loncom”, and the malware named as Trojan-Dropper.NSIS.Loncom.

Loncom packer utilizes the NSIS software to run the shellcode from the file named as ” 48510113″, and the shellcode is unpacked to the hard disk and loaded into the memory.

Microsoft Crypto API
NSIS archive contents

Shellcode using an algorithm to decrypting itself step by step, once it decrypts the several such iterations of block, Shellcode starts loading libraries and retrieving the addresses of required functions with the help of the APIHashing technique.

After that, Loncom decrypts the another payload with an AES-256 block cipher that contains the same Shellcode.

Researchers analysed and observed the structure of the NSIS installers and find the final payload that located above the shellcode.

Microsoft Crypto API
NSIS data structure

Accoding to Securelist report “we noticed packed specimens of Backdoor.Win32.DarkVNC and Trojan-Ransom.Win32.Sodin families, also known as REvil and Sodinokibi. The first is a type of backdoor used for controlling an infected machine via the VNC protocol. The second is a ransomware that encrypts the victim’s information and threatens to publish it.”

Researchers also found that the campaign Cobalt Strike utility that used by the professional pentesters and some time it abused by APT hacker groups.

“The command center of the sample that contained Cobalt Strike had previously been seen distributing CactusTorch, a utility for running shellcode present in Cobalt Strike modules, and the same Cobalt Strike packed with a different packer,” Researchers said.

You can read the complete technical analysis here.

Also Read: Kinsing Malware Attacks Misconfigured Open Docker Daemon API Ports


BB00BA9726F922E07CF243D3CCFC2B6E (Backdoor.Win32.DarkVNC)
EBE191BF77044961684DF51B88CA8D05 (Backdoor.Win32.DarkVNC)
4B4C98AC8F04680F7C529956CFE8519B (Trojan-Ransom.Win32.Sodin)
AEF8FBB5C64734093E78EB13E6FA7849 (Cobalt Strike)


Latest articles

Sleepy Pickle Exploit Let Attackers Exploit ML Models And Attack End-Users

Hackers are targeting, attacking, and exploiting ML models. They want to hack into these...

SolarWinds Serv-U Vulnerability Let Attackers Access sensitive files

SolarWinds released a security advisory for addressing a Directory Traversal vulnerability which allows a...

Smishing Triad Hackers Attacking Online Banking, E-Commerce AND Payment Systems Customers

Hackers often attack online banking platforms, e-commerce portals, and payment systems for illicit purposes.Resecurity...

Threat Actor Claiming Leak Of 5 Million Ecuador’s Citizen Database

A threat actor has claimed responsibility for leaking the personal data of 5 million...

Ascension Hack Caused By an Employee Who Downloaded a Malicious File

Ascension, a leading healthcare provider, has made significant strides in its investigation and recovery...

AWS Announced Malware Detection Tool For S3 Buckets

Amazon Web Services (AWS) has announced the general availability of Amazon GuardDuty Malware Protection...

Hackers Exploiting MS Office Editor Vulnerability to Deploy Keylogger

Researchers have identified a sophisticated cyberattack orchestrated by the notorious Kimsuky threat group.The...
BALAJI is an Ex-Security Researcher (Threat Research Labs) at Comodo Cybersecurity. Editor-in-Chief & Co-Founder - Cyber Security News & GBHackers On Security.

Free Webinar

API Vulnerability Scanning

71% of the internet traffic comes from APIs so APIs have become soft targets for hackers.Securing APIs is a simple workflow provided you find API specific vulnerabilities and protect them.In the upcoming webinar, join Vivek Gopalan, VP of Products at Indusface as he takes you through the fundamentals of API vulnerability scanning..
Key takeaways include:

  • Scan API endpoints for OWASP API Top 10 vulnerabilities
  • Perform API penetration testing for business logic vulnerabilities
  • Prioritize the most critical vulnerabilities with AcuRisQ
  • Workflow automation for this entire process

Related Articles