Thursday , March 13 2025

New QBot email attacks use PDF and WSF combo to install malware

QBot malware is now distributed in phishing campaigns utilizing PDFs and Windows Script Files (WSF) to infect Windows devices.

Qbot (aka QakBot) is a former banking trojan that evolved into malware that provides initial access to corporate networks for other threat actors. This initial access is done by dropping additional payloads, such as Cobalt StrikeBrute Ratel, and other malware that allows other threat actors to access the compromised device.

400+ IPs Exploiting Multiple SSRF Vulnerabilities

GreyNoise warns of a coordinated increase in the exploitation of Server-Side Request Forgery (SSRF) vulnerabilities across various platforms. "At least...
Read More
400+ IPs Exploiting Multiple SSRF Vulnerabilities

NVIDIA has released update for NVIDIA Riva

NVIDIA has released a software update for Riva to fix security vulnerabilities that could allow privilege escalation, data tampering, denial...
Read More
NVIDIA has released update for NVIDIA Riva

CVE-2025-24201
Apple fixes 0-day exploited in “extremely sophisticated attack”

On Tuesday, Apple fixed a critical zero-day vulnerability affecting nearly all supported iPhones and iPads. The company noted that it...
Read More
CVE-2025-24201  Apple fixes 0-day exploited in “extremely sophisticated attack”

Microsoft’s March 2025 updates fix 7 zero-day, 57 flaws

Microsoft's March 2025 Patch Tuesday update fixes 57 flaws, including seven zero-day exploits, six of which are actively being exploited....
Read More
Microsoft’s March 2025 updates fix 7 zero-day, 57 flaws

Ballista Botnet infects 6000 Unpatched TP-Link Routers

Cato CRTL team said, a new botnet campaign dubbed Ballista target the unpatched TP-Link Archer routers. CVE-2023-1389 is a serious...
Read More
Ballista Botnet infects 6000 Unpatched TP-Link Routers

CVE-2025-24813
Flaw in Apache Tomcat Exposes Servers to RCE

A critical vulnerability, CVE-2025-24813, has been found in Apache Tomcat, which could let attackers execute remote code, leak sensitive data,...
Read More
CVE-2025-24813  Flaw in Apache Tomcat Exposes Servers to RCE

CISA Adds 3 Ivanti Endpoint Manager Bugs to KEV

CISA included three vulnerabilities in Ivanti Endpoint Manager—CVE-2024-13159, CVE-2024-13160, and CVE-2024-13161—in its Known Exploited Vulnerabilities catalog. Federal agencies must address...
Read More
CISA Adds 3 Ivanti Endpoint Manager Bugs to KEV

Ransomware Attacks Set Records in February: New Data Shows

Ransomware attacks reached a record high in February, surpassing previous months, according to a Cyble report. The Cyble report tracked...
Read More
Ransomware Attacks Set Records in February: New Data Shows

Cyber attack at Japanese telecom leader NTT hits 18,000 companies

NTT Communications Corporation discovered illegal access to its facilities on February 5 and confirmed on February 6 that some information...
Read More
Cyber attack at Japanese telecom leader NTT hits 18,000 companies

Cyber heist: Pune losses Rs 6007 crore in cyber scam

India's Maharashtra Deputy Chief Minister Devendra Fadnavis disclosed alarming cyber fraud figures for Pune in 2024 during the Assembly session....
Read More
Cyber heist: Pune losses Rs 6007 crore in cyber scam
Using this access, the threat actors spread laterally through a network, stealing data and eventually deploying ransomware in extortion attacks.

Starting this month, security researcher ProxyLife and the Cryptolaemus group have been chronicling Qbot’s use of a new email distribution method — PDF attachments that download Windows Script Files to install Qbot on victim’s devices.

It starts with an email

QBot is currently being distributed through reply-chain phishing emails, when threat actors use stolen email exchanges and then reply to them with links to malware or malicious attachments.

The use of reply-chain emails is an attempt to make a phishing email less suspicious as its a reply to an ongoing conversation.

The phishing emails use a variety of languages, marking this as a worldwide malware distribution campaign.

QBot phishing email
QBot phishing email
Source: BleepingComputer

Attached to these emails is a PDF file named ‘CancelationLetter-[number].pdf ,’ that, when opened, displays a message stating, “This document contains protected files, to display them, click on the “open” button.”

However, when the button is clicked, a ZIP file that contains a Windows Script (wsf) file will be downloaded instead.

PDF document used to distribute malicious WSF files
PDF document used to distribute malicious WSF files
Source: BleepingComputer

A Windows Script File ends with a .wsf extension and can contain a mixture of JScript and VBScript code that is executed when the file is double-clicked.

The WSF file used in the QBot malware distribution campaign is heavily obfuscated, with the ultimate goal of executing a PowerShell script on the computer.

Malicious WSF file distributed by QBot PDF files
Malicious WSF file distributed by QBot PDF files
Source: BleepingComputer

The PowerShell script that is executed by the WSF file attempts to download a DLL from a list of URLs. Each URL is tried until the file is successfully downloaded to the %TEMP% folder and executed.

PowerShell script executed by the WSF file
PowerShell script executed by the WSF file
Source: BleepingComputer

When the QBot DLL is executed, it will run the PING command to determine if there is an internet connection. The malware will then inject itself into the legitimate Windows wermgr.exe (Windows Error Manager) program, where it will quietly run in the background.

QBot malware injected into the memory of the Wermgr.exe process
QBot malware injected into the memory of the Wermgr.exe process
Source: BleepingComputer

QBot malware infections can lead to devastating attacks on corporate networks, making it vital to understand how the malware is being distributed.

Ransomware affiliates linked to multiple Ransomware-as-a-Service (RaaS) operations, including BlackBasta, REvil, PwndLocker, EgregorProLock, and MegaCortex, have used Qbot for initial access into corporate networks.

Researchers at The DFIR Report have shown that it only takes around 30 minutes for QBot to steal sensitive data after the initial infection. Even worse, malicious activity only takes an hour to spread to adjacent workstations.

Therefore, if a device becomes infected with QBot, it is critical to take the system offline as soon as possible and perform a complete evaluation of the network for unusual behavior.

Check Also

Pune

Cyber heist: Pune losses Rs 6007 crore in cyber scam

India’s Maharashtra Deputy Chief Minister Devendra Fadnavis disclosed alarming cyber fraud figures for Pune in …

Leave a Reply

Your email address will not be published. Required fields are marked *