Latest coverage for Email

In early January 2026, KrebsOnSecurity revealed how a security researcher disclosed a vulnerability that was used to assemble Kimwolf, the world's largest and most disruptive botnet. Since then, the person in control of Kimwolf -- who goes by the handle "Dort" -- has coordinated a barrage of distributed denial-of-service (DDoS), doxing and email flooding attacks against the researcher and this author, and more recently caused a SWAT team to be sent to the researcher's home. This post examines what is knowable about Dort based on public information.

Cybercriminals are abusing a widespread lack of authentication in the customer service platform Zendesk to flood targeted email inboxes with menacing messages that come from hundreds of Zendesk corporate customers simultaneously.

The chairman of the Federal Trade Commission (FTC) last week sent a letter to Google's CEO demanding to know why Gmail was blocking messages from Republican senders while allegedly failing to block similar missives supporting Democrats. The letter followed media reports accusing Gmail of disproportionately flagging messages from the GOP fundraising platform WinRed and sending them to the spam folder. But according to experts who track daily spam volumes worldwide, WinRed's messages are getting blocked more because its methods of blasting email are increasingly way more spammy than that of ActBlue, the fundraising platform for Democrats.

KrebsOnSecurity recently heard from a reader whose boss's email account got phished and was used to trick one of the company's customers into sending a large payment to scammers. An investigation into the attacker's infrastructure points to a long-running Nigerian cybercrime group that is actively targeting established companies in the transportation and aviation industries.

A message posted on Monday to the homepage of the U.S. Cybersecurity & Infrastructure Security Agency (CISA) is the latest exhibit in the Trump administration's continued disregard for basic cybersecurity protections. The message instructed recently-fired CISA employees to get in touch so they can be rehired and then immediately placed on leave, asking employees to send their Social Security number or date of birth in a password-protected email attachment -- presumably with the password needed to view the file included in the body of the email.

Adam Griffin is still in disbelief over how quickly he was robbed of nearly $500,000 in cryptocurrencies. A scammer called using a real Google phone number to warn his Gmail account was being hacked, sent email security alerts directly from google.com, and ultimately seized control over the account by convincing him to click "yes" to a Google prompt on his mobile device.

The Federal Bureau of Investigation (FBI) is urging police departments and governments worldwide to beef up security around their email systems, citing a recent increase in cybercriminal services that use hacked police email accounts to send unauthorized subpoenas and customer data requests to U.S.-based technology companies.

Many GitHub users this week received a novel phishing email warning of critical security holes in their code. Those who clicked the link for details were asked to distinguish themselves from bots by pressing a combination of keyboard keys that causes Microsoft Windows to download password-stealing malware. While it's unlikely that many programmers fell for this scam, it's notable because less targeted versions of it are likely to be far more successful against the average Windows user.

An old but persistent email scam known as "sextortion" has a new personalized touch: The missives, which claim that malware has captured webcam footage of recipients pleasuring themselves, now include a photo of the target's home in a bid to make threats about publishing the videos more frightening and convincing.

Google says it recently fixed an authentication weakness that allowed crooks to circumvent email verification needed to create a Google Workspace account, and leverage that to impersonate a domain holder to third-party services that allow logins through Google's "Sign in with Google" feature.

At least a dozen organizations with domain names at domain registrar Squarespace saw their websites hijacked last week. Squarespace bought all assets of Google Domains a year ago, but many customers still haven't set up their new accounts. Experts say malicious hackers learned they could commandeer any migrated Squarespace accounts that hadn't yet been registered, merely by supplying an email address tied to an existing domain.

Thread hijacking attacks. They happen when someone you know has their email account compromised, and you are suddenly dropped into an existing conversation between the sender and someone else. These missives draw on the recipient's natural curiosity about being copied on a private discussion, which is modified to include a malicious link or attachment. Here's the story of a recent thread hijacking attack in which a journalist was copied on a phishing email from the unwilling subject of a recent scoop.

The Minnesota-based Internet provider U.S. Internet Corp. has a business unit called Securence, which specializes in providing filtered, secure email services to businesses, educational institutions and government agencies worldwide. But until it was notified last week, U.S. Internet was publishing more than a decade's worth of its internal email -- and that of thousands of Securence clients -- in plain text out on the Internet and just a click away for anyone with a Web browser.

When KrebsOnSecurity broke the news on Oct. 20, 2023 that identity and authentication giant Okta had suffered a breach in its customer support department, Okta said the intrusion allowed hackers to steal sensitive data from fewer than one percent of its 18,000+ customers. But today, Okta revised that impact statement, saying the attackers also stole the name and email address for nearly all of its customer support users.

In the summer of 2022, KrebsOnSecurity documented the plight of several readers who had their accounts at big-three consumer credit reporting bureau Experian hijacked after identity thieves simply re-registered the accounts using a different email address. Sixteen months later, Experian clearly has not addressed this gaping lack of security. I know that because my account at Experian was recently hijacked, and the only way I could recover access was by recreating the account.

One frustrating aspect of email phishing is the frequency with which scammers fall back on tried-and-true methods that really have no business working these days. Like attaching a phishing email to a traditional, clean email message, or leveraging link redirects on LinkedIn, or abusing an encoding method that makes it easy to disguise booby-trapped Microsoft Windows files as relatively harmless documents.

It's not often that a zero-day vulnerability causes a network security vendor to urge customers to physically remove and decommission an entire line of affected hardware -- as opposed to just applying software updates. But experts say that is exactly what transpired this week with Barracuda Networks, as the company struggled to combat a sprawling malware threat which appears to have undermined its email security appliances in such a fundamental way that they can no longer be safely updated with software fixes.

One of the most expensive aspects of any cybercriminal operation is the time and effort it takes to create large numbers of new throwaway email accounts. Now a new service offers to help dramatically cut costs associated with large-scale spam and account creation campaigns, by paying people to sell their email account credentials and letting customers temporarily rent access to a vast pool of established accounts at major providers.

Two U.S. men have been charged with hacking into a U.S. Drug Enforcement Agency (DEA) online portal that taps into 16 different federal law enforcement databases. Both are alleged to be part of a larger criminal organization that specializes in using fake emergency data requests from compromised police and government email accounts to publicly threaten and extort their victims.

Millions of people likely just received an email or snail mail notice saying they're eligible to claim a class action payment in connection with the 2017 megabreach at consumer credit bureau Equifax. Given the high volume of reader inquiries about this, it seemed worth pointing out that while this particular offer is legit (if paltry), scammers are likely to soon capitalize on public attention to the settlement money.