Beware WARMCOOKIE Backdoor Knocking Your Inbox

WARMCOOKIE is a new Windows backdoor that is deployed by a phishing effort with a recruiting theme dubbed REF6127.

The WARMCOOKIE backdoor can be used to take screenshots of the target computer, deliver additional payloads, and fingerprint a system.

“This malware represents a formidable threat that provides the capability to access target environments and push additional types of malware down to victims”, Elastic Security Labs shared with Cyber Security News.

WARMCOOKIE Execution Flow

Researchers have been observing phishing efforts that use lures associated with recruitment firms since late April 2024.

Free Webinar on API vulnerability scanning for OWASP API Top 10 vulnerabilities -> Book Your Spot.

By addressing recipients by name and their present employer, these emails enticed them to look for new employment by clicking on a link that would take them to an internal system where they could read a job description.

Phishing email – Subject: “We’re Interested”

After clicking, users are taken to a landing page that appears to be an authentic website that was created only for them. 

There, they must complete a CAPTCHA test to download a document. The landing pages, which mention a new variation of URSNIF, are similar to earlier campaigns that Google Cloud’s security team has identified.

WARMCOOKIE attack flow

When the CAPTCHA is solved, an obfuscated JavaScript file is downloaded from the page. This obfuscated script launches PowerShell, initiating the initial task to load WARMCOOKIE.

The PowerShell script uses the Background Intelligent Transfer Service (BITS) to download WARMCOOKIE and launch the DLL. 

Researchers note that 45.9.74[.]135 is the IP address where the threat actor continuously and swiftly creates new landing pages.

The actor made an effort to target several hiring agencies while combining industry-related keywords.

Domains associated with 45.9.74[.]135

The backdoor gathers the following values before sending its first outgoing network request, and they are used to identify and fingerprint the target system.

  • Volume serial number
  • DNS domain of the victim machine
  • Computer name
  • Username

In particular, the malware that can take screenshots from victims’ computers offers a variety of harmful possibilities, like making use of private data that is visible on the screen or keeping a close eye on the victim’s computer. 

Screen capture

According to analysts, threat actors create new infrastructure and domains every week to support these campaigns.

“While there is room for improvement on the malware development side, we believe these minor issues will be addressed over time,” researchers conclude.

Free Webinar! 3 Security Trends to Maximize MSP Growth -> Register For Free

Guru baran

Gurubaran is a co-founder of Cyber Security News and GBHackers On Security. He has 10+ years of experience as a Security Consultant, Editor, and Analyst in cybersecurity, technology, and communications.

Recent Posts

Hackers Claiming Dettol Data Breach: 453,646 users Impacted

A significant data breach has been reported by a threat actor known as 'Hana,' who claims to have compromised the…

21 hours ago

CrowdStrike Update Triggers Widespread Windows BSOD Crashes

A recent update from cybersecurity firm CrowdStrike has caused significant disruptions for Windows users, leading to widespread reports of Blue…

1 day ago

Operation Spincaster Disrupts Approval Phishing Technique that Drains Victim’s Wallets

Chainalysis has launched Operation Spincaster, an initiative to disrupt approval phishing scams that have drained billions from victims' wallets. This…

1 day ago

Octo Tempest Know for Attacking VMWare ESXi Servers Added RansomHub & Qilin to Its Arsenal

Threat actors often attack VMware ESXi servers since they accommodate many virtual machines, which link to a variety of systems…

2 days ago

TAG-100 Actors Using Open-Source Tools To Attack Gov & Private Orgs

Hackers exploit open-source tools to execute attacks because they are readily available, well-documented, and often have extensive community support, making…

2 days ago

macOS Users Beware Of Weaponized Meeting App From North Korean Hackers

Meeting apps are often targeted and turned into weapons by hackers as they are largely employed for communication and collaboration,…

2 days ago