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    BeginnerLes 3 van 5·Foundations

    Spotting Phishing — The Four Red Flags You Can Always Trust

    Phishing comes in many forms — email, SMS, voice, QR, chat, video — but almost every variant has the same four red flags: a request for action, urgency or pressure, a channel mismatch, and a credibility prop that doesn't quite hold up. Learn these four and you'll spot 90% of attempts without needing to be a security expert.

    Reviewed by the HackersHub team — updated 13 May 20266 min readVrij te gebruiken — CC-BY-ND 4.0

    Het scenario

    A receptionist at a Rotterdam law firm gets an email from the managing partner: 'Hi — quick favour, I'm in client meetings all morning. Can you grab me five €50 Bol.com vouchers and send the codes? It's for a team birthday surprise, please don't tell anyone. I'll reimburse you this afternoon.' The signature line matches the partner's normal sign-off. The email address looks right at a glance. The pretext is plausible — vouchers are a normal team-gift category. But four red flags are present: the request asks for an unusual action (vouchers, not normal work), there is urgency ('this morning'), there is a channel mismatch (partner usually walks over for personal favours, doesn't email finance), and the secrecy ask ('don't tell anyone') is the credibility prop that doesn't hold up — real surprise-gifts use the office assistant, not the front-desk receptionist. The receptionist walks across the office to the partner's desk. The partner has no idea what she is talking about. The lure is forwarded to IT — who report 14 other firms in the same building received variants the same morning.

    Hoe de aanval werkt

    Almost every phishing variant — email, SMS, voice, QR, chat, deepfake video — shares the same four-element structure. **Red flag 1: a request for action.** The lure asks you to DO something — click, pay, transfer, sign in, read aloud, install. Pure information emails ('your invoice is ready, log in via the app') are usually safer than action-demanding emails. **Red flag 2: urgency or pressure.** Time pressure ('before close of business', 'expires in 24 hours'), authority pressure ('your manager wants this'), or consequence pressure ('your account will be closed') is engineered to short-circuit thinking. **Red flag 3: a channel mismatch.** The request arrives via a channel the legitimate sender doesn't normally use, or asks you to switch to a new channel ('don't reply to email, just call this new number'). Real organisations stay in their normal channels. **Red flag 4: a credibility prop that doesn't quite hold up.** A look-alike sender domain, slightly wrong tone of voice, a missing or odd signature, weird grammar, or pretextual details that contradict each other ('grab the vouchers, don't tell anyone'). The phisher has to put SOMETHING credible in front of you — but they can rarely make the entire context perfect. The combination of one or two red flags should already raise suspicion; three or four is the lure itself. The other modules in this Foundations track and the full Phishing track go deeper on each variant; this lesson is the universal pattern.

    Waar je op moet letten

    • Requests for action — clicks, payments, transfers, sign-ins, OTPs, software installs, document approvals
    • Urgency framing — deadlines, audit pressure, authority pressure, fear of consequence
    • Channel mismatch — sender using a different channel than they normally would, or pushing you to switch channels
    • Credibility props that don't quite hold up — domain mismatch, tone mismatch, missing details, contradictory context
    • ANY communication asking you to bypass your normal workflow ('skip the approval', 'don't loop in finance', 'I'll explain later')

    Wat te doen

    1. Use the four-red-flags test on any suspicious messageIf two or more are present, treat as phishing until verified. Three or more = the lure itself.
    2. Verify out-of-band — on a channel the sender already uses with youWalk over, call them on a number you have in your records, or DM them on a platform you know they use. Never call a number from the suspicious message.
    3. Report — use your mail client's 'Report Phishing' button or forward to security with full headersReporting is free, fast, and identifies attacks targeting your colleagues simultaneously.
    4. Never act on urgency before verifying — the urgency is the trapReal urgent requests survive a 2-minute verification call. Phishing ones don't.

    Verdediging — voor IT en beleid

    Technische controles

    • DMARC enforcement on your domain (stops easy spoofing)
    • Phishing-resistant MFA (FIDO2/passkeys) — defeats credential-stealing phishing kits even if a click happens
    • Email gateway with link rewriting + attachment detonation

    Beleidscontroles

    • Written 'IT will never ask you to read aloud OTPs or click MFA-reset links from email or SMS' rule, reinforced quarterly
    • Two-person rule on payment-instruction changes
    • Reporting button on every mail client, no-blame culture

    Trainingsfrequentie

    Pair this with monthly simulated phishing. Measure reporting rate first, click rate second.

    Korte check

    Vijf vragen. Antwoorden en toelichting verschijnen na inzenden.

    1. Q1.

      Which of these is NOT one of the four universal phishing red flags?

    2. Q2.

      Two of the four red flags appear in a message. What is your correct response?

    3. Q3.

      A coworker DMs you a link in Slack asking you to 'log in to the new IT portal'. The DM was unsolicited and the link domain is unfamiliar. Most likely:

    4. Q4.

      Which type of verification is genuinely safe?

    5. Q5.

      Is urgency by itself enough to flag a message as phishing?

    Bronnen & verdere lectuur

    Verwante modules

    Wil je een echte aanvaller in je omgeving testen?

    HackersHub voert betaalde red-team-engagements uit.

    Praat met een expert

    Deze module is door HackersHub goedgekeurd in exact deze vorm, inclusief watermerk. Gratis onder CC-BY-ND 4.0. Wil je de inhoud aanpassen? Verwijder dan eerst ons watermerk. — Het HackersHub-team Bekijk licentievoorwaarden.