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Cybercriminals Weaponize Legitimate Japanese ISP Infrastructure in Multi-Wave Campaign
In an alarming development, cybersecurity researchers at Raven have uncovered a highly sophisticated phishing campaign that managed to bypass most traditional email defenses. What sets this campaign apart is not just its technical prowess but its cunning use of legitimate platforms to deliver malicious content. Instead of spoofing domains or using fake sendersâcommon tactics in phishing attemptsâthe attackers cleverly exploited Nifty.com, a trusted Japanese internet service provider (ISP), to send authenticated phishing emails that easily slipped past secure email gateways.
This campaign showcases a new era of phishing, where threat actors use legitimate infrastructure and advanced evasion methods to remain undetected. The attacks were not only technically complex but also strategically timed and thematically consistent, mimicking business-related communication such as execution agreements and SAFE contracts. This deliberate targeting of professional workflows, paired with automation, suggests the involvement of sophisticated phishing toolkitsâpossibly powered by AI.
As the campaign evolved through multiple waves from late April into May, it demonstrated adaptive behavior and a keen awareness of security detection mechanisms. Raven’s detection and investigation highlight how phishing has evolved far beyond poorly written emails and suspicious links. Now, attackers use professional-looking attachments, redirection chains, and email authentication protocols to carry out stealthy credential harvesting campaignsâposing a serious challenge to outdated cybersecurity models.
Behind the Mask: Inside the Multi-Wave Phishing Operation
The campaign began quietly on April 28 with emails disguised as “Execution Agreements.” Instead of sending emails from suspicious domains, the attackers used real accounts created on Nifty.comâa reputable ISPâto send their phishing messages. Because these emails came from legitimate infrastructure and passed key email authentication protocols like SPF, DKIM, and DMARC, they sailed through most email filters and reached inboxes without raising red flags.
Over the following weeks, the attackers evolved their strategy. They repeated the theme with different labels, such as âSAFE agreement,â to increase their chances of success. In the final phase of the campaign, there was a noticeable uptick in email volume, with dozens being sent within minutesâsignaling automation and the likely use of preconfigured phishing kits.
The emails were crafted with impressive attention to detail. They lacked the hallmarks of typical phishing, such as grammar mistakes or odd formatting. The body of the email contained no malicious links. Instead, the phishing payloads were hidden inside attachmentsâmostly PDFs and HTML filesânamed in a way to seem relevant to business activities. These HTML attachments used redirect chains, beginning with seemingly innocent marketing trackers, that ultimately led victims to phishing sites hosted on obscure domains. These sites used heavily obfuscated JavaScript and included recipient identifiers embedded in the URLs for personalized tracking.
To further evade detection, the attackers used advanced tricks like HTML padding, MIME encoding, and spoofed display names like “Name via DocuSign.” These emails looked exactly like legitimate business messages, making them highly effective at deceiving recipients.
Despite the effort to appear benign, Ravenâs threat detection systems caught subtle anomaliesâsuch as strange sender-recipient relationships, repeated use of identical attachments, and behavior patterns inconsistent with genuine business communication. Eventually, the redirect chains were linked to malicious infrastructure, confirming the phishing intent.
The ultimate goal of this campaign was to steal login credentials and session tokens, especially for Gmail. Given the complexity and precision of the attacks, security researchers believe that the perpetrators used automated systems and high-quality phishing kits, possibly enhanced with AI.
This incident demonstrates that traditional defenses, which rely heavily on flagging suspicious content or authentication failures, are no longer sufficient. The attackers cleverly used authenticated, clean emails that blended into regular traffic, revealing the urgent need for smarter, behavior-based email security solutions.
What Undercode Say:
This phishing operation represents a turning point in cyberattack strategy. It’s not just another email scamâitâs a blueprint for how cybercriminals can weaponize trust. By hijacking a legitimate ISP’s infrastructure and following proper email authentication procedures, attackers now have the means to walk right past most of the defenses companies have in place.
What’s particularly dangerous is the campaignâs avoidance of the usual phishing triggers. These emails were clean on the surfaceâno suspicious domains, no broken language, and no spammy formatting. Instead, the attackers embedded their traps within innocuous attachments and routed their victims through a maze of redirects that only the most advanced detection tools could trace.
The use of business-related lures such as âExecution Agreementsâ and âSAFE contractsâ shows a high level of social engineering. Itâs clear that these messages were tailored for professionals, aiming to exploit everyday workflows. This is not just opportunistic phishingâitâs highly targeted, well-researched, and supported by automation.
What weâre seeing is the evolution of phishing from sloppy scams to professional campaigns. With phishing kits possibly powered by AI, threat actors can now produce error-free, convincing emails that look better than the real thing. That changes the entire playing field.
The abuse of platforms like Nifty.com also reveals a serious blind spot in current email security practices. Most systems are still built around blocking bad actors. But what happens when the bad actors look good on paper? Thatâs the challenge this campaign exposes.
Behavioral analysis, zero-trust architecture, and anomaly detection are now essential. It’s not enough to look at where an email comes fromâyou need to analyze how it behaves, who itâs targeting, and what itâs trying to accomplish.
For security teams, this incident is a wake-up call. Automation, email authentication, and clean delivery paths are no longer signs of safety. They might just be signs of a smarter, stealthier threat.
If this approach becomes widespread, we could be looking at a new norm where phishing campaigns become indistinguishable from legitimate business emailsâunless youâre actively monitoring context, behavior, and intent. The arms race has escalated.
Fact Checker Results:
â The campaign abused authenticated Nifty.com accounts
â Advanced phishing kits and automation likely involved
â Traditional email defenses failed due to trust-based infrastructure use
Prediction:
Expect a rise in phishing campaigns leveraging trusted domains and email infrastructure. Cybercriminals will increasingly use legitimate services, paired with automation and AI, to craft indistinguishable phishing emails. Security systems will need to pivot from static rules to behavioral and contextual analysis to remain effective.
References:
Reported By: cyberpress.org
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