Privilege escalation

Privilege escalation is the act of exploiting a

Most computer systems are designed for use with multiple user accounts, each of which has abilities known as privileges. Common privileges include viewing and editing files or modifying system files.

Privilege escalation means users receive privileges they are not entitled to. These privileges can be used to delete files, view private information, or install unwanted programs such as viruses. It usually occurs when a system has a bug that allows security to be bypassed or, alternatively, has flawed design assumptions about how it will be used. Privilege escalation occurs in two forms:

• Vertical privilege escalation, also known as privilege elevation, where a lower privilege user or application accesses functions or content reserved for higher privilege users or applications (e.g. Internet Banking users can access site administrative functions or the password for a smartphone can be bypassed.)
• Horizontal privilege escalation, where a normal user accesses functions or content reserved for other normal users (e.g. Internet Banking User A accesses the Internet bank account of User B)

Vertical

This type of

Examples

In some cases, a high-privilege application assumes that it would only be provided with input matching its interface specification, thus doesn't validate this input. Then, an attacker may be able to exploit this assumption, in order to run unauthorized code with the application's privileges:

• Some Windows services are configured to run under the Local System user account. A vulnerability such as a buffer overflow may be used to execute arbitrary code with privilege elevated to Local System. Alternatively, a system service that is impersonating a lesser user can elevate that user's privileges if errors are not handled correctly while the user is being impersonated (e.g. if the user has introduced a malicious error handler)
• Under some legacy versions of the Microsoft Windows operating system, the All Users screensaver runs under the Local System account – any account that can replace the current screensaver binary in the file system or Registry can therefore elevate privileges.
• In certain versions of the
  killed by another process. The core dump file would have been placed at the program's current directory, that is, /etc/cron.d, and cron would have treated it as a text file instructing it to run programs on schedule. Because the contents of the file would be under attacker's control, the attacker would be able to execute any program with root
  privileges.
• Cross Zone Scripting
  is a type of privilege escalation attack in which a website subverts the security model of web browsers, thus allowing it to run malicious code on client computers.
• There are also situations where an application can use other high privilege services and has incorrect assumptions about how a client could manipulate its use of these services. An application that can execute
  Command line or shell commands could have a Shell Injection
  vulnerability if it uses unvalidated input as part of an executed command. An attacker would then be able to run system commands using the application's privileges.
• TI-Nspire, for which jailbreaks using Ndless
  have been found but are still actively fought against by Texas Instruments.)
• Some versions of the iPhone allow an unauthorised user to access the phone while it is locked.^[1]

Jailbreaking

In computer security, jailbreaking is defined as the act of removing limitations that a vendor attempted to hard-code into its software or services.

Jailbreaking can also occur in systems and software that use generative artificial intelligence models, such as ChatGPT. In jailbreaking attacks on artificial intelligence systems, users are able to manipulate the model to behave differently than it was programmed, making it possible to reveal information about how the model was instructed and induce it to respond in an anomalous or harmful way.^[9][10]

Android

Android phones can be officially rooted by either going through manufacturers controlled process, using an exploit to gain root, or flashing custom recovery. Manufacturers allow rooting through a process they control, while some allow the phone to be rooted simply by pressing specific key combinations at boot time, or by other self-administered methods. Using a manufacturers method almost always factory resets the device, making rooting useless to people who want to view the data, and also voids the warranty permanently, even if the device is derooted and reflashed. Software exploits commonly either target a root-level process that is accessible to the user, by using an exploit specific to the phone's kernel, or using a known Android exploit that has been patched in newer versions; by not upgrading the phone, or intentionally downgrading the version.

Mitigation strategies

Operating systems and users can use the following strategies to reduce the risk of privilege escalation:

• Data Execution Prevention
• Address space layout randomization (to make it harder for buffer overruns to execute privileged instructions at known addresses in memory)
• Running applications with least privilege (for example by running Internet Explorer with the Administrator SID disabled in the process token) in order to reduce the ability of buffer overrun exploits to abuse the privileges of an elevated user.
• Requiring kernel mode code to be digitally signed.
• Patching
• Use of compilers that trap buffer overruns^[11]
• Encryption of software and/or firmware components.
• Use of an operating system with Mandatory Access Controls (MAC) such as
  SELinux^[12]
• Kernel Data Relocation Mechanism (dynamically relocates privilege information in the running kernel, preventing privilege escalation attacks using memory corruption)

Recent research has shown what can effectively provide protection against privilege escalation attacks. These include the proposal of the additional kernel observer (AKO), which specifically prevents attacks focused on OS vulnerabilities. Research shows that AKO is in fact effective against privilege escalation attacks.[13]

Horizontal

Horizontal privilege escalation occurs when an application allows the attacker to gain access to

This problem often occurs in web applications. Consider the following example:

• User A has access to their own bank account in an Internet Banking application.
• User B has access to their own bank account in the same Internet Banking application.
• The vulnerability occurs when User A is able to access User B's bank account by performing some sort of malicious activity.

This malicious activity may be possible due to common web application weaknesses or vulnerabilities.

Potential web application vulnerabilities or situations that may lead to this condition include:

• Predictable session IDs in the user's HTTP cookie
• Session fixation
• Cross-site scripting
• Easily guessable passwords
• Theft or hijacking of session cookies
• Keystroke logging

See also

• Cybersecurity
• Defensive programming
• Hacking of consumer electronics
• Illegal number
• Principle of least privilege
• Privilege revocation (computing)
• Privilege separation
• Rooting (Android OS)
• Row hammer

References