Wednesday, May 21, 2025
HomeCloudAhoi Attacks - New Attack Breaking VMs With Malicious Interrupts

Ahoi Attacks – New Attack Breaking VMs With Malicious Interrupts

Published on

SIEM as a Service

Follow Us on Google News

Ahoy, which is often associated with communicating to ships, has now been playfully adopted in pirate language.

We coin ‘Ahoi,’ an anagram of ‘Iago,’ to pay tribute to research on interface attacks with TEEs.

Confidential computing, also referred to as trusted execution, protects sensitive computations on public cloud platforms. 

- Advertisement - Google News

Hardware vendors provide trusted hardware that guarantees user code and data security from malicious actors.

Ahoi Attacks

Cloud providers now offer confidential computing via technologies like Intel SGX for process-level isolation and AMD SEV, Intel TDX, and ARM CCA for VM-level isolation as Confidential VMs (CVMs). 

SGX enclaves isolate single processes from other processes/OS, while CVMs allow deploying entire isolated VMs inaccessible to other tenants, provider’s hardware/software like hypervisors.

Document
Stop Advanced Phishing Attack With AI

AI-Powered Protection for Business Email Security

Trustifi’s Advanced threat protection prevents the widest spectrum of sophisticated attacks before they reach a user’s mailbox. Stopping 99% of phishing attacks missed by other email security solutions. .

CVMs enable better cloud-native confidential computing abstraction than SGX’s process-level model.

Interrupt management is done almost entirely by the hypervisor in CVMs. CVM security can be breached by Ahoi attacks using notifications.

The hypervisor virtualizes the delivery of interrupts necessary for the operation of CVMs.

This hooks physical interrupts, redirects them to corresponding virtual machines, and raises virtual interrupts.

As a result, the guest OS within this CVM handles these interrupts via their handlers and ultimately acknowledges them.

The hardware exception is mapped in “x86” to the interrupts 0 through 31.

An example of this is when a divide-by-zero occurs and raises interrupt 0, which the OS converts to SIGFPE for user-space delivery.

Applying for a custom handler is like calculating the non-weighted average of SIGFPE.

Ahoi attacks have virtual CPUs that are attacked using a hypervisor to inject malicious interrupts into them, which helps invoke interrupt handlers globally.

Execution flow leading to successful authentication (Source – Github)

Ahoi attacks can take advantage of the interrupts and signals, which were made for trusted hypervisor environments.

Projects like Heckler can demonstrate this, as they have demonstrated how to breach AMD SEV-SNP and Intel TDX to gain unauthorized access to CVMs. 

Moreover, such vulnerabilities extend even up to specialized interrupt interfaces such as AMD SEV’s VMM Communication Exception (#VC) meant for safe hypervisor-CVM communication. 

However, this interface can be used by hypervisors to perform malicious tasks that are executed without being caught by CVMs.

WeSee exploits AMD SEV-SNP’s flaws to do forbidden things on CVMs.

Secure your emails in a heartbeat! To find your ideal email security vendor, Take a Free 30-Second Assessment.

Tushar Subhra
Tushar Subhra
Tushar is a Cyber security content editor with a passion for creating captivating and informative content. With years of experience under his belt in Cyber Security, he is covering Cyber Security News, technology and other news.

Latest articles

Malicious Hackers Create Fake AI Tool to Exploit Millions of Users

A concerning development in the field of cybersecurity is the initiation of a sophisticated...

New Phishing Attack Uses AES & Malicious npm Packages to Office 365 Login Credentials

Fortra’s Suspicious Email Analysis (SEA) team uncovered a highly sophisticated phishing campaign targeting Microsoft...

Kettering Health Experiences System-Wide Outage Due to Ransomware Attack

Kettering Health, a major healthcare provider, has been hit by what appears to be...

Critical Vulnerability in Lexmark Printers Enables Remote Code Execution

Security researchers from DEVCORE discovered the vulnerability through Trend Micro’s Zero Day Initiative (ZDI),...

Resilience at Scale

Why Application Security is Non-Negotiable

The resilience of your digital infrastructure directly impacts your ability to scale. And yet, application security remains a critical weak link for most organizations.

Application Security is no longer just a defensive play—it’s the cornerstone of cyber resilience and sustainable growth. In this webinar, Karthik Krishnamoorthy (CTO of Indusface) and Phani Deepak Akella (VP of Marketing – Indusface), will share how AI-powered application security can help organizations build resilience by

Discussion points


Protecting at internet scale using AI and behavioral-based DDoS & bot mitigation.
Autonomously discovering external assets and remediating vulnerabilities within 72 hours, enabling secure, confident scaling.
Ensuring 100% application availability through platforms architected for failure resilience.
Eliminating silos with real-time correlation between attack surface and active threats for rapid, accurate mitigation

More like this

New Phishing Attack Uses AES & Malicious npm Packages to Office 365 Login Credentials

Fortra’s Suspicious Email Analysis (SEA) team uncovered a highly sophisticated phishing campaign targeting Microsoft...

Kettering Health Experiences System-Wide Outage Due to Ransomware Attack

Kettering Health, a major healthcare provider, has been hit by what appears to be...

Hazy Hawk Targets DNS Vulnerabilities to Hijack Cloud Resources and Spread Malware

The threat actor gained attention in February 2025 after successfully hijacking a subdomain of...