computer science

XARA

XARA is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand XARA rather than just read about it. In short: XARA (Cross-App Resource Access) is a class of vulnerabilities that allows malicious applications to gain unauthorized access to resources belonging to other applications running on the same operating system. First extensively documented in 2015 by researchers at Indiana University, Georgia Tech, and Peking University, XARA vulnerabilities represent significant security threats to modern sandboxed computing environm…

Key takeaways

XARA belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect XARA to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of XARA from memory before moving on to harder problems.

Reference excerpt

XARA (Cross-App Resource Access) is a class of vulnerabilities that allows malicious applications to gain unauthorized access to resources belonging to other applications running on the same operating system. First extensively documented in 2015 by researchers at Indiana University, Georgia Tech, and Peking University, XARA vulnerabilities represent significant security threats to modern sandboxed computing environments, particularly on macOS, iOS; similar inter-app vulnerabilities have also been identified on Android. XARA attacks exploit weaknesses in inter-process communication mechanisms and access control policies, enabling attackers to bypass the principle of least privilege in sandboxed applications. Examples include unauthorized access to keychain items, URL scheme hijacking, WebSocket hijacking, and app container cracking. These vulnerabilities can lead to theft of authentication credentials and personal data without requiring privilege escalation or jailbreaking. The 2015 XARA disclosure prompted security enhancements in major operating systems, such as stricter sandbox controls on macOS and iOS. However, new variants continue to emerge as application ecosystems become more complex and interconnected.

Initial Disclosure An academic research paper entitled "Unauthorized Cross-App Resource Access on MAC OS X and iOS". was published on 26 May 2015 by a team of researchers from Indiana University, Tsinghua University, Peking University, Chinese Academy of Sciences, and Georgia Institute of Technology. The paper was widely released to the public on 16 June 2015 and commented on by both mainstream and technical media outlets. The paper identifies a number of separate categories of zero day threats to applications and stored passwords which can potentially be exploited by malware on iOS devices and OS X. The paper also discloses the existence of similar vulnerabilities on Android devices.

Response by Vendors On 19 June 2015, Apple Computer responded to the press that they had implemented countermeasures to exclude malware containing the XARA exploit from their iOS App Store.

Attack Vectors In XARA each attack vector violates the principles of a computer security sandbox.

Untrusted partners using shared resources such file system, keychain. Inter-process communication without verification of partner. Weak security policies of system installer allow other applications to be designated as shared resource bundles.

Known systems with problems iOS from Apple Computer OS X from Apple Computer Android from Google

See also Targeted attacks Access Control Software-defined protection Sandbox (computer security) Vector (malware)

References

Worked examples

Example 1 — a first encounter with XARA

Start with the simplest possible case. Write down what XARA claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to XARA before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about XARA ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of XARA

In research: XARA appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses XARA in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: XARA is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer network security, Types of malware, so understanding it makes those chapters shorter.
In everyday life: Look for XARA outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study XARA in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what XARA means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain XARA out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is XARA in simple terms?

Why does XARA matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study XARA?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on XARA.