Spoofy: checks if a list of domains can be spoofed based on SPF and DMARC records
Spoofy
Spoofy is a program that checks if a list of domains can be spoofed based on SPF and DMARC records. You may be asking, “Why do we need another tool that can check if a domain can be spoofed?”
Well, Spoofy is different, and here is why:
- Authoritative lookups on all lookups with known fallback (Cloudflare DNS)
- Accurate bulk lookups
- Custom, manually tested spoof logic (No guessing or speculating, real world test results)
- SPF lookup counter
HOW DO YOU KNOW ITS SPOOFABLE
(The spoofability table lists every combination of SPF and DMARC configurations that impact deliverability to the inbox, except for DKIM modifiers.) Download Here
METHODOLOGY
The creation of the spoofability table involved listing every relevant SPF and DMARC configuration, combining them, and then conducting SPF and DMARC information collection using an early version of Spoofy on a large number of US government domains. Testing if an SPF and DMARC combination was spoofable or not was done using the email security pentesting suite at emailspooftest using Microsoft 365. However, the initial testing was conducted using Protonmail and Gmail, but these services were found to utilize reverse lookup checks that affected the results, particularly for subdomain spoof testing. As a result, Microsoft 365 was used for the testing, as it offered greater control over the handling of mail.
After the initial testing using Microsoft 365, some combinations were retested using Protonmail and Gmail due to the differences in their handling of banners in emails. Protonmail and Gmail can place spoofed mail in the inbox with a banner or in spam without a banner, leading to some SPF and DMARC combinations being reported as “Mailbox Dependent” when using Spoofy. In contrast, Microsoft 365 places both conditions in spam. The testing and data collection process took several days to complete, after which a good master table was compiled and used as the basis for the Spoofy spoofability logic.
