Bug Bounty LFI at [Google.com]

VulnerabilityLabs
May 24 · 4 min read

GOOGLE BUG BOUNTY: LFI ON PRODUCTION SERVERS IN “SPRINGBOARD.GOOGLE.COM” — $13,337 USD

Hi everyone It’s been a while from my last post but I’m back, I want to tell you a short story about my greatest find so far (My first P1)

It was in Google VRP program and why you can always check for dirs in 301 / 302 / 403 / 404 status pages because you will surprise that some times some directories listing will work:

FIRST ROUND

Title: Auth bypass in springboard.google.com
Product / URL: ​springboard.google.com/REDACTED_DIR

Report sent via google VRP program https://goo.gl/vulnz

Summary:

Authorization bypass in https://springboard.google.com/REDACTED_DIR and see “OnContent Debug for” mini dashboard

POC:

1.- Go to https://springboard.google.com/ and got redirected to https://cloudsearch.google.com/cloudsearch/error?et=6 and see the message

2.- Then navigate to https://springboard.google.com/REDACTED_DIR and see a mini dashboard with the form:

3 days after that I got a message:

At first glance, this might not be severe enough to qualify for a reward, though the panel will take a look shortly.

Spoiler:

Unfortunately, after a week, I got the reply that from google VRP Panel:

“As a part of our Vulnerability Reward Program, we decided that it does not meet the bar for a financial reward

SECOND ROUND

Since the bug probably won’t be elegible to get a financial reward, I started thinking to go deeper on that “Auth bypass”, I mean, for some reason is not suppoused to be open, so I decided to try again, then after some new dir enumeration with wfuzz, I got something really really interesting, I was able to escalate that simple Auth bypass bug to LFI on production servers as admin in google production servers.

Title: LFI on production servers in the same subdomain
Product / URL: ​springboard.google.com/REDACTED_DIR/ANOTHER_DIR

Summary:

I’ve able to escalate this auth bypass to LFI on google production servers as “gxx-xxxx” user (admin privileges)!

POC:

1.- First see that the dashboard panel of “Redacted status main” (FrameworkInfo) is open in https://springboard.google.com/REDACTED_DIR/ANOTHER_DIR

2.- Then if you navigate to “Show REDACTED” (The last option) you are going to be redirected to https://springboard.google.com/REDACTED_DIR/ANOTHER_DIR?file=/proc/self/environ and the /proc/self/environ will be loaded

3.- Just to be sure that was a full LFI working I tried to load another file and I checked with /proc/version and works just as expected!

Then my heart stopped for a second, I just got a LFI on google production servers as administrator (servers on plural because each time that I refreshed /proc/self/environ file the hostname changed)

To be honest I tried to escalate to RCE but I hadn’t any success, since apparently it was very hardened I wasn’t able to read /proc/*/fd, ssh keys, server keys or any logs.

Environment

Any browser (I used Google Chrome Lastest version)
No authentication or any Google account was needed

Report Timeline

Mar 22, 2019: Sent the report to Google VRP (Just the bypass auth part)
Mar 22, 2019: Got a message from google that the bug was triaged
Mar 25, 2019: Bug Accepted
Mar 25, 2019: Reply about that the bug was in revision in Googgle VRP panel
Mar 30, 2019: I found the LFI and sent the new POC in the same report
Apr 1, 2019: Got a message saying that they going to fill a another bug with this LFI information
Apr 4, 2019: Got a message saying that the first bug wasn’t elegible for financial reward
Apr 17 ,2019: Since the everything was happening in the same report and the bugs were fixed, I asked to the team if the 2 bugs wasn’t elegibles or what happened
Apr 23, 2019: Got a message saying that sorry about the confusion and I just had to wait to a new reward decision for the LFI part.
May 21 2019: $13,337 bounty and permission to publish this write up received

VulnerabilityLabs

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Contact : vulnlabs.contact@gmail.com

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