---
title: "What are BreakSPF attacks and how can you defend against them? | AutoSPF"
description: "In today’s digital age, email is the most commonly used mode of communication. It is simple and quick, which is its greatest strength and biggest vulnerability."
image: "https://autospf.com/og/blog/what-are-breakspf-attacks-how-to-defend-against-them.png"
canonical: "https://autospf.com/blog/what-are-breakspf-attacks-how-to-defend-against-them/"
---

Quick Answer

In today’s digital age, email is the most commonly used mode of communication. It is simple and quick, which is its greatest strength and biggest vulnerability. When emails were introduced, the focus was on functionality rather than security, which left gaps for malicious actors to exploit.

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![BreakSPF attacks](https://media.mailhop.org/autospf/images/2024/11/how-to-create-spf-record-5364.jpg) 

In today’s digital age, email is the most commonly used mode of communication. It is simple and quick, which is its greatest strength and biggest vulnerability. When emails were introduced, the focus was on functionality rather than security, which left gaps for [malicious actors](https://cybernews.com/news/malicious-actors-leak-us-criminal-database/) to exploit. 

As emails became a frequent target for [cybercriminals](https://www.voanews.com/a/alleged-leader-of-cybercriminals-extradited-to-us/7741605.html) to launch phishing, spoofing, and other [malicious attacks](https://www.independent.co.uk/news/uk/politics/china-government-oliver-dowden-cameron-tim-loughton-b2518516.html), experts developed email authentication mechanisms like Sender Policy Framework (SPF) to tackle them. SPF provides protection against [spoofing emails](https://www.bleepingcomputer.com/news/google/google-now-blocks-spoofed-emails-for-better-phishing-protection/) by checking if the server sending emails is authorized by the domain owner to do so. In this case, it adds a trust factor to the message and gives the recipient the peace of mind that the message has come from a valid source. But despite its strong defense, it is not foolproof. 

Attackers have found a way to work around the safeguards of this protocol and exploit gaps in how [SPF](/blog/what-is-spf-email-a-guide-to-sender-validation-technology/) is implemented and processed. The technique they employ to do so is fairly new and is called BreakSPF. Since this technique is relatively novel, most organizations don’t even know exactly what it is, its implications, and how to protect against them. 

If you’ve also never heard of this attack framework before, you’re in the right place! _In this article, we will take you through everything you need to know about these attacks and how to defend against them._

## What are BreakSPF attacks and how are they different from other email-based attacks?

BreakSPF attacks prey on vulnerabilities in the Sender Policy Framework, particularly in cases where organizations use shared [email infrastructures](https://www.voilanorbert.com/blog/email-infrastructure/), such as cloud email services, proxies, or CDNs ([Content Delivery Networks](https://www.ibm.com/topics/content-delivery-networks)). These systems often rely on a vast pool of shared IP addresses, which are also updated on the [SPF records](/spf-record-checker/create-spf-record/). Attackers take advantage of this fact by findinglegitimate IPs within such ranges and sending forged emails that appear to originate from a trusted domain. Si\_nce such emails are authorized in the ‘legitimate’ range in the SPF record, they pass the authentication checks seamlessly and land in the inboxes\_.

What makes them different from typical email-based phishing or [spoofing attacks](https://www.forbes.com/sites/davidbalaban/2024/01/31/the-underestimated-scourge-of-spoofing-attacks/) is that they do not depend on trickery or malware but instead work around loopholes in how SPF is configured. For example, a complicated SPF record that has too many IP addresses. When this happens, the system can’t properly validate the sender, giving attackers a way in. This makes [BreakSPF attacks](https://securityboulevard.com/2024/11/breakspf-attacks-outsmart-the-hackers-and-protect-your-email/) more technical, focusing on exploiting system vulnerabilities rather than human errors.

![Email Spoofing](https://media.mailhop.org/autospf/images/2024/11/spf-checker-4963.jpg) 

## How does BreakSPF work?

Did you know that over [50% of the domains have SPF records that include more than 65,000](https://www.researchgate.net/publication/373144390%5FBreakSPF%5FHow%5FShared%5FInfrastructures%5FMagnify%5FSPF%5FVulnerabilities%5FAcross%5Fthe%5FInternet) IP addresses? That’s far more than what most domains need. Not to mention, the broader the range, the riskier it becomes. After all, [cyber attackers](https://www.infosecurity-magazine.com/news/cyber-attack-exposes-credit-card/) get more opportunities toidentify vulnerabilities and target them. 

Apart from this, when an SPF record is overly and unnecessarily complex, it exceeds the limit of 10 [DNS lookups](https://www.digicert.com/faq/dns/how-does-dns-lookup-work) and inevitably fails SPF validation. When this happens, the security layer meant to protect against fake emails stops working. 

Let’s see how attackers leverage this loophole:

- They spot a weak domain with very lenient SPF records that permit a huge list of IP addresses.
- They then identify the specific IPs in that list that fall within the range allowed by the target domain’s SPF record. The attackers use publicly available tools to do so.
- Hackers then send spoofs from valid IPs. Since these IPs are on the domain’s SPF record, the spoof emails pass the [SPF checks](/generative-ai-and-phishing-threats/spf-records-check/).
- If the domain’s DMARC policy is contingent on SPF for authentication, spoofed emails pass DMARC checks and appear authentic.
- Since spoofed emails bypass all standard email authentication measures, they reach the recipient’s inbox, where they perceive them as legitimate and coming from a trusted source.

## What are the different kinds of BreakSPF attacks?

BreakSPF attacks can be executed through various methods, depending on how attackers manipulate email transmission channels, particularly [HTTP servers](https://hyperskill.org/learn/step/25834) and [SMTP servers](https://www.brevo.com/blog/what-is-smtp-server/). These are broadly classified into 3 categories, each of which presents a unique challenge for detection and defense. Let us take a look at them:

### Fixed IP address attacks

This type of attack happens when an attacker uses specific IP addresses for a long time, taking control of them to send spoofed emails directly to the victim’s email service. Here, the attackers present themselves as Mail Transfer Agents (MTAs) and make use of shared services, like cloud servers or [proxy networks](https://en.wikipedia.org/wiki/Proxy%5FNetworks,%5FInc.), to launch their attacks. In this case, [traditional defenses](https://www.techradar.com/pro/attackers-new-way-to-outsmart-traditional-defenses-is-by-weaponizing-legitimate-software) like greylisting prove ineffective as they operate on the assumption that spammers use disposable IPs or servers. _However, with such attacks, the use of stable, controlled IPs by attackers gives them an edge over the defenses_. 

### Dynamic IP address attacks

Here, attackers don’t stick to a single outgoing IP address. Instead, they work dynamically; they determine which domains are vulnerable and can be exploited based on the IP address that they are using at the moment. This gives them [temporary access](https://www.aljazeera.com/news/2023/4/19/us-supreme-court-upholds-temporary-restrictions-on-abortion-pill) to send spoofed emails without needing permanent control over the IPs.

Such attacks typically rely on [public infrastructure](https://www.salesforce.com/in/blog/what-is-public-infrastructure/) like serverless platforms or [continuous integration/continuous deployment](https://www.geeksforgeeks.org/what-is-ci-cd/) (CI/CD) systems. Moreover, since the outgoing IPs are constantly changing, traditional defenses like blocklisting IP addresses aren’t as effective, making [dynamic attacks](https://www.atlantafalcons.com/news/falcons-offensive-line-kirk-cousins-jake-matthews) more difficult to stop.

![Cross-Protocol attacks](https://media.mailhop.org/autospf/images/2024/11/spf-validator-3.jpg) 

### Cross-Protocol attacks

The attacker does not need to take control of any IP addresses directly in [cross-protocol attacks](https://thehackernews.com/2021/06/new-tls-attack-lets-attackers-launch.html). Instead, they embed the SMTP data inside HTTP data and then send them to the victim’s email service through shared infrastructure such as open HTTP proxies orCDN exit nodes. Since these attacks essentially disguise SMTP traffic as normal web traffic, these are very difficult to detect or trace, as they exploit the transparency or trust associated with heavily used [web infrastructure](https://www.wix.com/blog/website-infrastructure).

## What are the implications of BreakSPF attacks?

Although BreakSPF is a novel [cyber threat](https://apnews.com/article/fbi-china-espionage-hacking-db23dd96cfd825e4988852a34a99d4ea), its impact can be quite damaging for both individuals and businesses. Let’s decode how:

When hackers use this technique to send spoofed emails, they essentially trick unsuspecting users into sharing sensitive information, such as passwords or [financial data](https://cyberscoop.com/treasury-report-cyber-risks-ai-tools/). For businesses, this means losing critical data and the trust of their customers or partners, who might not trust any email coming from the organization, even the legitimate ones. 

![hackers](https://media.mailhop.org/autospf/images/2024/11/sender-policy-framework-office-365-2.jpg) 

That is not all, though. [Reputational loss can cause damage](https://civil.ge/archives/626799) in terms of finances, customers, and market position. It might compel people to stop buying from a brand they no longer trust, which affects sales and the bottom line. _All the effort put into building a strong, reliable brand image can be undone with one successful attack_. That is to say, the impact of BreakSPF goes beyond security; it touches every aspect of the business’s operations and relationships.

Looking at the bigger picture, these attacks hurt more than just businesses; they make people lose faith in email as a secure mode of communication. Once they start losing their trust in emails, they will eventually avoid using them for professional or personal purposes. This will disrupt everything from daily communication to [marketing campaigns](https://www.investopedia.com/terms/m/marketing-campaign.asp) that depend on emails to reach people.

## How can you protect your organization from BreakSPF attacks?

BreakSPF attacks are gaining momentum in the [cybersecurity](/10-reasons-for-regular-spf-record-checks-in-cybersecurity/) circles, particularly among cyber attackers. This means that organizations and security teams need to step up and take proactive measures to protect themselves. 

Here’s what you can do to safeguard your organization:

![Cybersecurity](https://media.mailhop.org/autospf/images/2024/11/spf-record-generator-3.jpg) 

### Keep your SPF records clean and simple

Go through your SPF records, ensuring that they only include the [email servers](https://www.one.com/en/email/what-is-an-email-server) you’re really using. _Do not add large ranges of IP addresses unless necessary. The simpler your SPF record is, the fewer opportunities hackers have to exploit it_.

### Stay within SPF limits

SPF can only process a maximum of 10 DNS lookups. If your SPF record is too complex and surpasses the limit, your emails will fail SPF checks or be [flagged as suspicious](https://www.wsj.com/articles/new-rules-will-force-buyout-firms-to-flag-suspicious-investments-2c7d4449). This is why it is important to stay within the lookup limit of 10\. To stay within the limit, remove unnecessary ‘include’ statements or nested IPs and consider [SPF flattening tools](/?%5Fgl=1%2A1op2v35%2A%5Fup%2AMQ..%2A%5Fga%2ANDYxMTAwMzgxLjE3MjMwMzcwMDI.%2A%5Fga%5F5J0R8M01Y5%2AMTcyMzAzNzAwMS4xLjAuMTcyMzAzNzAwMS4wLjAuMA..). 

### Properly configure authentication protocols 

The primary goal of BreakSPF attacks is to exploit misconfigurations in SPF and DMARC to bypass verification checks, and attackers are most often successful in this. They capitalize on misconfigurations like incorrect setup of SPF and [DMARC records](/10-reasons-for-regular-spf-record-checks-in-cybersecurity/dmarc-record-check/), outdated configurations, or failure to optimize settings regularly. However, you can prevent them by identifying and addressing any loopholes in how these protocols are implemented. 

![unauthorized emails
](https://media.mailhop.org/autospf/images/2024/11/spf-lookup-5.jpg)

When configuring DMARC, be sure to use a strict policy like ‘reject’ or ‘quarantine,’ which will keep [unauthorized emails](https://news.trendmicro.com/2023/12/05/unauthorized-log-in-attempt-notification-email/) at bay. 

## The way forward

_On the face of it, it might look like implementing email authentication protocol is a one-time task. But in reality, it requires continuous monitoring, updating, and optimization_. If you’re struggling with implementing SPF or managing your SPF records, our team at AutoSPF is here to help you! Reach out to us today to simplify your [email authentication](/spf-too-many-dns-lookups/spf-lookup/) process.

## Topics

[ SPF ](/tags/spf/)[ SPF Flattening tool ](/tags/spf-flattening-tool/)[ SPF record ](/tags/spf-record/) 

![Brad Slavin](https://media.mailhop.org/autospf/images/authors/brad-slavin.jpg) 

[ Brad Slavin ](/authors/brad-slavin/) 

General Manager

Founder and General Manager of DuoCircle. Product strategy and commercial lead for AutoSPF's 2,000+ customer base.

[LinkedIn Profile →](https://www.linkedin.com/in/bradslavin) 

## Ready to get started?

Try AutoSPF free — no credit card required.

[ Book a Demo ](/book-a-demo/) 

## Related Articles

[  Intermediate 3m  3 points to consider before setting your SPF record to -all (HardFail)  May 22, 2025 ](/blog/3-points-to-consider-before-setting-your-spf-record-hardfail/)[  Intermediate 6m  6 Best practices for maintaining an SPF record  Jun 5, 2025 ](/blog/6-best-practices-for-maintaining-an-spf-record/)[  Intermediate 3m  Adding your SPF record to your domain provider  Sep 2, 2024 ](/blog/adding-your-spf-record-to-your-domain-provider/)[  Intermediate 6m  Your SPF record is broken- What does it mean and how do you fix it?  Jan 16, 2025 ](/blog/broken-spf-record-meaning-and-how-to-fix-it/)

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