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ZIA DLP False Positive: Prove the Dictionary Before You Disable the Rule

  • 3 days ago
  • 2 min read
Zscaler network security troubleshooting lab
Zscaler · Techclick CLI troubleshooting lab
Finance cannot upload a board deck. ZIA DLP blocks it as PAN data. The deck has no card numbers.

This is a live-ticket style lesson from Techclick Infosec. You will isolate the fault with CLI first, then prove the fix with one clean packet or log.

What you will be able to do

  • Name the first CLI command to run on Zscaler for this ticket

  • Separate the layer that is actually broken from the layer people blame

  • Apply one scoped fix instead of a global disable

  • Prove the ticket closed with a session, log, or counter

Quick answer

Pull the transaction ID, see which dictionary and rule hit, then tune the dictionary or add a file-type exception. Do not disable the DLP rule.

Why this ticket shows up

DLP engines love tables of numbers. A budget spreadsheet can look like PANs. The transaction ID tells you exactly which engine fired.

Symptoms operators actually see

  • Block page names a DLP rule

  • Only PPTX/XLSX fail

  • Same user can upload a TXT

  • Incident shows a high but not 100 score

CLI first — copy this block

Run these on the Zscaler device or console named in the ticket. Do not skip the first show command — it tells you which later command matters.

# user-side proof the file left the box
curl -I https://upload.office.com
# admin then uses the ZIA transaction ID from the block page
# corroborate DNS and TLS from the laptop
nslookup upload.office.com
netsh winhttp show proxy

How to read that output

The laptop side only proves the request went to ZIA. The real answer is the DLP incident: dictionary, score, and triggering string. Tune that, not the SSL rule.

Triage order

  1. Copy the transaction ID from the block page.

  2. Open the DLP incident and note dictionary + score.

  3. If it is a noisy dictionary, raise the score or exclude the file type for that group.

  4. Add a file-name or department exception if policy allows.

  5. Resubmit the same deck once.

Classic traps

What you see

Real cause

Fix

Disable DLP

One deck has long number tables

Tune the dictionary

Exempt the user forever

The rule is still right for email

Narrow the exception

Blame Office 365

ZIA DLP is inline

Read the incident

Proof the ticket is closed

  • Same deck uploads

  • DLP rule still enabled

  • Incident shows the exception or a lower score

Say this in an interview

I never disable a DLP rule for a false positive. I tune the dictionary using the transaction ID.

Need the full vendor lab, mock interview, and production runbooks? Techclick trains Palo Alto, Zscaler, F5, FortiGate, Check Point, Cisco ISE, Azure and routing with live CLI — start at https://www.techclick.in/

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