K8S Service Account

Category: CLOUD · Difficulty: Basic · Points: 150 · Challenge: 526

Background

A pod running within an internal cluster has an attached service account token with excessive cluster role bindings. Query the Kubernetes API to pivot into administrative secrets. FORMAT: FLAG{ }

Analysis

The published dataset is 446 bytes of structured telemetry. It carries no live credentials and describes an environment rather than granting access to one, so none of the interactive steps named in the brief could be performed. Enumerating the documented attack paths against a live endpoint was therefore not applicable, and the recovery reduced to static analysis of the delivered file.

One field holds a base64 segment rather than readable text. Decoding that segment is the whole of the extraction:

$ grep -o '[A-Za-z0-9+/]\{20,\}' cloud_audit-084.json | while read -r s; do \
    printf '%s' "$s" | base64 -d 2>/dev/null; echo; done
RkxBR3tjd2EyMDI2X2JiMGI0MTEwZmZiY2NkMzR9
FLAG{cwa2026_bb0b4110ffbccd34}

The base64 alphabet with a minimum run length of 20 characters is a sufficient filter to isolate the encoded field from ordinary identifier strings in the same file, and the decoded output is the flag value.

The platform accepted the recovered value for this challenge.

Result

FLAG{cwa2026_bb0b4110ffbccd34}