Exploiting Application & File Vulnerabilities

AP Cybersecurity · Securing Applications and Data

Exploiting Application and File Vulnerabilities

Files are protected by encryption and permissions. Remove either and possession becomes access.

key ideaFiles are protected by encryption and permissions. Remove either and possession becomes access.

The idea

The baseline problem

An adversary can read any unencrypted file if they have access to the device or drive storing it. Every other control in this topic exists because that sentence is true — physical or logical possession of storage is, by default, possession of the contents.

Privilege and permission

Computers have standard users and administrative users. Administrative users can control system settings and typically access any files or applications on the system. Granting that level to regular users hands an adversary the same reach the moment one account is compromised.

The three failures compound. Weak access control decides who can reach a file; excessive privilege decides how much one compromised account is worth; and missing encryption decides whether reaching it is enough.

Data at restFiles stored on a drive. Unencrypted, they are readable by anyone who reaches the device.

Standard userAn account limited to its own work — the default every user should have.

Administrative userAn account that can control system settings and typically access any file or application on the system.

Access control settingsWhat decides which users can view and edit which files. Weakly configured, they grant far more than anyone needs.

Least privilegeGiving each account exactly the access its function requires, and no more.

Weakness	How an adversary exploits it	What it costs
unencrypted files	obtains the device or drive and reads them	confidentiality, entirely
regular users with admin rights	compromises one ordinary account	any file or application on the system, plus system settings
weak access control	uses a legitimate account to view files it should not reach	confidentiality across far more data than the account needs
edit permissions granted too widely	alters files rather than only reading them	integrity — and the change may go unnoticed

Row 4 is the quiet one. Read access loses confidentiality; write access loses integrity, and a modified file rarely announces itself the way a missing one does.

Why it works that way

Operating systems answer ‘may this account open this file?’ from the permissions attached to it. If those permissions are generous, the system is behaving correctly when it grants access — which is why over-permissioned data is invisible to most monitoring.

four consequences

An unencrypted file offers no defense once the storage is reached.
An administrative account typically reaches any file or application on the system.
Weak access control lets many users view and sometimes edit files — both matter.
Access granted legitimately does not look like an attack in the logs.

Encryptiondecides if reaching it is enough

Privilegedecides how much one account is worth

Permissionsdecide who reaches it at all

Access control is two decisions, not one. Granting write because read was already granted is how altered records enter a system — and an altered record is harder to notice than a missing one.

Worked analysis

EX 1

The stolen laptop

A laptop is stolen. It has a strong login password, and its files are not encrypted. What can the thief read?

Note what the password protects

The operating system login — not the drive.

State the bypass

Remove the drive, attach it to another machine, and the OS is out of the picture.

Apply the CED statement

An adversary can read any unencrypted file if they have access to the device or drive storing it.

State what would have helped

Full-disk encryption — the drive is unreadable without the key.

Note the layering

The password protects against a casual user; encryption protects against someone holding the hardware.

EX 2

Everyone is an administrator

A small firm makes every employee a local administrator “so IT does not get bothered”. Assess.

State what administrators can do

Control system settings and typically access any files or applications on the system.

Apply it to a compromise

Phishing one ordinary user now yields administrative access.

Note the second effect

Malware runs with full rights — it can disable protections and persist.

Give the control

Standard accounts by default, with elevation only when required and logged.

Address the original complaint

The convenience is real; the answer is a fast elevation process, not permanent privilege.

EX 3

The share everyone can edit

A file share holding contracts is readable and writable by all staff. Nothing has gone wrong yet. What is the risk?

Name the confidentiality risk

Weak access control settings mean many users can view files they have no need for.

Name the integrity risk

Write access means a contract can be altered — accidentally or deliberately.

Note the detection difficulty

Both actions are permitted, so they generate no alerts.

Give the control

Restrict to the roles that need it, and separate read from write.

State the principle

Access that is granted is access that will eventually be used — by someone, at some point.

Common traps

A login password is not disk encryption

It protects the running system. An adversary who removes the drive never sees the login screen at all.

Administrative rights are not a convenience setting

They grant control of system settings and access to any file or application. Every account that has them is a full compromise waiting to happen.

Weak access control is invisible

The system grants what the permissions allow, so over-broad access never appears as an error. It has to be audited deliberately.

Edit permission is a separate decision from read

Read loses confidentiality; write loses integrity. Granting both because it was easier is how altered records go unnoticed.

Check yourself

What can an adversary do with unencrypted files?

Show answer

They can read any unencrypted file if they have access to the device or drive storing it — regardless of the operating system's login controls.

What is the difference between standard and administrative users?

Show answer

Administrative users have access to control system settings and can typically access any files or applications on a system. Standard users cannot.

Why is giving regular users administrative rights dangerous?

Show answer

Compromising any one ordinary account then yields administrative access to the whole system — and malware running under that account inherits the same reach.

What do weakly configured access control settings allow?

Show answer

Many users gain permission to view, and sometimes edit, files on a system. Adversaries with any legitimate account can then reach data that account never needed.

Course map. Topic 5.1.a · LO 5.1.A — explain how adversaries can exploit application and file vulnerabilities to cause loss, damage, disruption, or destruction (EK 5.1.A.1–5.1.A.3: reading any unencrypted file with access to the device or drive; standard versus administrative users and the risk of granting administrative rights broadly; weakly configured access control settings letting many users view and sometimes edit files).