RedTeam IDs

Sep 25, 2025

TODAY’S TOPIC — Red Team IDs / MIFARE Polyglot Cards !

  • To request: send name + image; if you sent it in time, printed IDs are ready for pickup.
  • Last year: printed on inkjet labels before we had a card printer.. improvements made!

Background Info…

  • For the RedTeam IDs → using proxmark for writing data to cards.
  • Two main chip vendors: HID and NXP (high-freq vs low-freq).
  • Our Husky cards use NFC / MIFARE Classic

Security Stuff…

  • MIFARE Classic is insecure. VERY Poor encryption.
    • Uses the proprietary Crypto1 cypher (widely analyzed/pwned since ~2008). Very bad.
    • Still commonly used in access control despite vulnerabilities.
  • Each card has a factory UID/serial number; this is readable and supposed to be changed.. but they don’t
  • Cards use sectors and keys (Key A / Key B) and contain access bits and manufacturer data.
  • Readers often convert UID to an upstream value (e.g., a Wiegand code) that the door controller uses to grant access.

IMPORTANT TO NOTE…

  • We disclosed findings to IT; they were not concerned, but do not hand out cards or impersonate others.
  • Stay within Tech/IT policy boundaries and avoid actions that would get the club in trouble. (Covering our asses.)

Polyglot / Multi-format Cards

  • A polyglot (2-in-1) card can present multiple formats (e.g., our Husky format + another).
  • Some readers (e.g., Schlage/Allegion) support multi-card types — nice for the organization - also nice for us… we can do a downgrade attack (we don’t need to, we already have the worst type).
  • readers try sector 15 as well, not sure why
  • move sector 1 to sector 15→ tada!

Tools

  • Mentioned tools: MIFARE Classic Tool (Android), Proxmark3, Flipper Zero, ChameleonUltra.
  • Buy the proxmark3 off of alibaba.
  • Equipment is available to check out through RedTeam (return like library items).

Audience Time!!

  • Take out your husky cards and flip it! (back numbers → facility code & card number are printed/readable).
  • Our card numbers are straight up printed , if you read someones’ card number you could hypothetically make a copy of their card (don’t do this)

Other Topics / Events

  • Car Hackathon (Yu Cai): embedded car hackathon using Raspberry Pis → ~2 days, team auto-balancing, $500/$400/$300 rewards for 1st/2nd/3rd places! sign-up using the QR in presentation.
  • More info here, and you can sign up here!