Thursday, March 28, 2024

Hackers Attack MS Exchange Servers Using ProxyShell & ProxyLogon Exploits to Distribute Malware

Hackers are Targeting Microsoft Exchange servers using exploits to distribute malware. The vulnerabilities allow hackers to bypass detection by sending emails with malware attachments or messages containing malicious links to internal employees. This is done by abusing the Exchange server’s built-in features, ProxyShell and ProxyLogon.

Threat actors use a number of strategies to mislead the user into opening the email and clicking on the malicious attachment. They can impersonate a legitimate sender, include a sense of urgency or click-bait subject line, or use a low-quality crafted email that looks like it was sent from an unprofessional company.

TrendMicro researchers have discovered a clever tactic of using compromised Microsoft Exchange servers to distribute malicious emails to a company’s internal users. 

All this is done by sending an infected email to the victim and then forwarding it to all of the victim’s contacts in their address book.

The emails will appear to be sent from the victim’s own account and the subject line will be formatted like a normal email.

Microsoft Exchange infection

It is believed that the hackers behind this attack are from the ‘TR’ group, it’s a well-known hacker group that distributes emails with malicious attachments that drop malware. Even TR has been spotted in the past using the following file formats in their emails:-

  • Microsoft Office Files (.doc, .xls, .ppt)
  • Rich Text Format (.rtf) 
  • Portable Document Format (.pdf)
  • Single File Web Page (.mht)
  • Compiled HTML (.chm)
  • Compiled Help File (.chm or .hlp)
  • Shell Executable files (.exe, .com, or .bat)

The payloads that are used are:-

  • Qbot
  • IcedID
  • Cobalt Strike
  • SquirrelWaffle

Moreover, Trend Micro has claimed that “In the same intrusion, we analyzed the email headers for the received malicious emails, the mail path was internal (between the three internal exchange servers’ mailboxes), indicating that the emails did not originate from an external sender, open mail relay, or any message transfer agent (MTA).”

Since these emails are coming from the same internal network, it is safe to assume that they are legitimate. The tone of the emails is conversational while still maintaining a professional tone.

It’s an excellent tactic used by hackers for not raising any alarms on the email protection systems.

Vulnerabilities Exploited

Here are the vulnerabilities that are exploited:-

  • CVE-2021-34473: The pre-auth path confusion
  • CVE-2021-34523: Exchange PowerShell backend elevation-of-privilege
  • CVE-2021-26855: The pre-authentication proxy vulnerability

Always keep your Exchange servers updated

For later backdoor access the hackers deploy ransomware or install webshells by exploiting both ProxyShell and ProxyLogon vulnerabilities. And these attacks god so bad that without informing the servers’ owners the FBI removed webshells from all the available compromised US-based Microsoft Exchange servers.

That’s why the cybersecurity experts strongly recommend users immediately update their Exchange servers, and make sure the firewall is up to date and well configured. 

Even you should also make sure that you’re running the latest version of the anti-malware software for your operating system. If you’re not sure, then contact your IT support provider.

You can follow us on LinkedinTwitterFacebook for daily Cybersecurity, and hacking news updates.

Website

Latest articles

Wireshark 4.2.4 Released: What’s New!

Wireshark stands as the undisputed leader, offering unparalleled tools for troubleshooting, analysis, development, and...

Zoom Unveils AI-Powered All-In-One AI Work Workplace

Zoom has taken a monumental leap forward by introducing Zoom Workplace, an all-encompassing AI-powered...

iPhone Users Beware! Darcula Phishing Service Attacking Via iMessage

Phishing allows hackers to exploit human vulnerabilities and trick users into revealing sensitive information...

2 Chrome Zero-Days Exploited at Pwn2Own 2024: Patch Now

Google has announced a crucial update to its Chrome browser, addressing several vulnerabilities, including...

The Moon Malware Hacked 6,000 ASUS Routers in 72hours to Use for Proxy

Black Lotus Labs discovered a multi-year campaign by TheMoon malware targeting vulnerable routers and...

Hackers Actively Exploiting Ray AI Framework Flaw to Hack Thousands of Servers

A critical vulnerability in Ray, an open-source AI framework that is widely utilized across...
Balaji
Balaji
BALAJI is an Ex-Security Researcher (Threat Research Labs) at Comodo Cybersecurity. Editor-in-Chief & Co-Founder - Cyber Security News & GBHackers On Security.

Mitigating Vulnerability Types & 0-day Threats

Mitigating Vulnerability & 0-day Threats

Alert Fatigue that helps no one as security teams need to triage 100s of vulnerabilities.

  • The problem of vulnerability fatigue today
  • Difference between CVSS-specific vulnerability vs risk-based vulnerability
  • Evaluating vulnerabilities based on the business impact/risk
  • Automation to reduce alert fatigue and enhance security posture significantly

Related Articles