HOW HACKERS EXPLOIT INTERNAL FILE SHARES

ARTICLES

Winston. I

12/20/20252 min read

INTRODUCTION

Most people imagine hacking as breaking into systems, bypassing defenses, or exploiting vulnerabilities. In reality, some of the most damaging breaches involve none of that. Attackers simply access file shares that were never meant to be public.

Internal file shares exist to make work easier. Over time, they accumulate sensitive data: credentials, backups, exports, diagrams, notes, and scripts. Access controls loosen, users come and go, and nobody remembers what’s actually stored inside.

This walkthrough shows how attackers exploit internal file shares after initial access.

WHY FILE SHARES ARE A GOLDMINE

File shares are dangerous because they:

  • Are trusted by default

  • Contain historical data

  • Are rarely monitored

  • Are shared across teams

  • Often outlive their purpose

Attackers don’t need admin access to benefit from them. They just need any valid login.

STEP 1: INITIAL ACCESS

In most real incidents, access to the internal network has already been achieved:

  • stolen VPN credentials

  • compromised workstation

  • reused password

  • phishing

At this stage, the attacker looks like a normal employee.

STEP 2: DISCOVERING FILE SHARES

Once inside, attackers enumerate available file shares.

STEP 3: ACCESSING A “NON-SENSITIVE” SHARE

Attackers usually start with the least protected share often called Public, Shared, or Common. These are assumed to be harmless.

STEP 4: BROWSING FILES (THE BORING PART)

Most of the time, attackers don’t find anything immediately useful.

STEP 5: FINDING SOMETHING “SMALL”

Attackers open files that look harmless. Notes. Text files. Old documents.

STEP 6: REALIZING THIS ISN’T AN ACCIDENT

That credential likely:

  • still exists

  • was shared across systems

  • has more access than intended

  • was never rotated

Attackers don’t rush. They verify quietly.

STEP 7: ACCESSING A RESTRICTED SHARE

Now the attacker tries the credential on another share.

STEP 8: THE REAL DAMAGE

Inside engineering shares, attackers often find:

  • network diagrams

  • scripts

  • configs

  • credentials for other systems

  • backup archives