Knowledge · IT · Data · DX

Software Reverse Analysis and the Law · Program Code Reverse Analysis

Legal Limits of Software Reverse Engineering

📂IT·Data·DX⏱2-min read📊Advanced🔗7 related

What is the law on reverse engineering software?

In one line
The rules that set how far you may take apart someone else's software. In Korea, the program code reverse analysis provision of the Copyright Act, trade secret protections, and the product's terms of use together draw the line.
Bring this topic to in-house training📚 Related Course💬 Ask About Training
⚡ Summary in 3 lines
  • The Copyright Act allows analysis only for compatibility
  • A terms-of-use ban on reverse analysis binds the company
  • Integration is fine; copying is risky

Just because reverse engineering has become technically easy doesn't make the legal call easy. Article 101-4 of the Copyright Act says that when a person lawfully using a program cannot easily obtain information needed for compatibility with another program, they may analyze the program code, only to that extent, without the rights holder's permission. Conversely, using that information for purposes other than compatibility, passing it to others, or using it to build a substantially similar program is prohibited. The exception allows analysis 'to interoperate', not 'to copy'.

The second boundary is contract. Many commercial software and SaaS terms of service include a ban on reverse analysis and decompilation, and once your company clicks “I agree,” those terms bind it. Even where the law allows the analysis, violating the terms can lead to contract termination or damages claims. The third is trade secrets. Information learned by analyzing a lawfully obtained product is generally not treated as trade secret misappropriation, but if the analysis involved unauthorized access to the other party’s server or violated account rules, other laws such as the Information and Communications Network Act may apply.

Good records matter too, in case of a dispute. Documenting what you analyzed, under what authority, and for what purpose makes it easier to prove later that the purpose was interoperability. Conversely, handing analysis results straight to the development team invites disputes over whether the newly written code copied the analysis results, so some companies use a clean-room approach that separates the people who analyze from the people who implement.

Three questions decide the matter in practice: Who owns the target, and what rights do we have over it? Do the terms of use prohibit reverse analysis? And where will the results be used? Targets with clear rights and a clear purpose are relatively safe, such as a company-owned legacy system, contractor-delivered work that you have a contractual right to inspect and accept, or a security review. Analysis aimed at replicating a competitor app's features is the riskiest. Now that AI tools let anyone run an analysis, writing permitted targets and approval procedures into your internal AI usage policy is the cheapest way to prevent incidents. Specific cases must always go through legal review.

Courses that cover this term · AI & DX
Recommended courses · Recommended instructors · Quick quote
📚Building Guardrails So AI Doesn’t Make Mistakes — Harness Engineering for Non-Developers4 hours · In-person corporate training · John KimSee course →📚Vibe Coding Security — Safety-Checking the AI Web Apps You Built4 hours · In-person corporate training · John KimSee course →
Instructor Jaryong KooJaryong KooMarketing PhD and leading authority on AI, data analytics, and personal brandingInstructor Seolyeong ParkSeolyeong ParkGenerative AI and AX training specialist with 17 years of hands-on experience and 200+ sessions, making AI usable even for non-specialists
🧮 Mini quote · Based on instructor fees
About KRW 1.2 million (≈ US$900)2-hour talk · up to 20 people · Korean
Get a quote for these requirements →
💡 In plain English
It's like studying an original part to find one that fits your car: fine. Stamping out identical copies to sell is where the trouble starts.
Why it matters in practice
As tools like REA let non-developers take software apart, the technical barrier is gone and only the legal judgment remains. Set the permitted targets and the approval process before an incident happens.
⚠️ Common misconceptions
MythSoftware you paid for is yours to take apart however you like.
FactSoftware is usually licensed, not owned, so a terms-of-use ban on reverse analysis applies as written. The legal exception is also narrow: only the parts necessary for compatibility.
Origin and sources

The 1991 EU Computer Programs Directive was the first to expressly permit decompilation for compatibility. In the US, the 1992 Sega v. Accolade ruling held that reverse analysis for compatibility is fair use. In Korea, the provision from the former Computer Programs Protection Act was folded into the Copyright Act in 2009 and now appears as Article 101-4.

Source · Copyright Act, Article 101-4 (Program Code Reverse Analysis) · View original
An example

Consider a hypothetical case. The planning team at Company A, a B2B training platform with 180 employees, heard that a competitor’s learning app had a popular 'automatic learning recommendation' feature. They proposed using an AI agent to analyze that app and build the same feature.

  1. Team Lead Ryu of the Planning team said that analyzing a competitor app with REA could reveal its recommendation logic within a week, and submitted the request for approval with the development team's schedule already booked.
  2. At the approval stage, Legal Manager Moon checked the competitor app's terms of use and found an explicit ban on reverse engineering and decompiling. The goal wasn't compatibility, either. It was copying features.
  3. Manager Moon put the analysis on hold, saying, “It doesn’t fit any of the permitted conditions, and using the results could even be seen as developing a similar program.”
  4. Instead, the planning team worked out the feature’s requirements themselves, through interviews with contacts at 20 of its own customers and observation of publicly available usage screens. Development then proceeded from scratch with its own design.
  5. After this episode, Company A added a rule to its internal AI usage policy: analyzing external software requires prior Legal approval. Over the next six months, 4 of 6 approval requests were approved, all for analysis of company-owned systems.
Related terms
Reverse EngineeringTaking a finished product or piece of software apart to find out how it was built and how it works. Because it recovers a design from the end result without the blueprints, it is also called reverse design.Decompiling · DisassemblingTurning a program that has been converted into unreadable machine code back into a readable form. Disassembling converts machine code into assembly language; decompiling goes one step further and restores it to a high-level language such as C.REA · Reverse Engineer AnythingAn open-source MCP server and command-line tool that connects AI coding agents to reverse engineering tools such as Ghidra and IDA, so they can analyze how apps and programs work without source code. REA stands for Reverse Engineer Anything.AI-Generated Works CopyrightThe questions of who holds the rights to AI-generated output and whether training data is lawful. Major countries today, including Korea, do not grant copyright to works generated solely by AI without 'human creative contribution'.IP Strategy · Patent MapA strategy for acquiring, using, and defending intangible assets such as patents, trademarks, and copyrights in line with business goals, plus a patent analysis map that shows technology trends at a glance.Internal AI Usage GuidelinesAn internal policy document that sets what information must never be entered, who is responsible for verification, and how outputs must be labeled when employees use generative AI at work.Teardown · Product AnalysisAn analysis method that takes a competing product or well-made service apart piece by piece, by component, screen, or step, and works backward to understand why it was designed that way. In marketing, it is used to dissect a competitor’s landing page, content request process, and follow-up email flow step by step.
Training linked to this term
📚Build a Framework So AI Doesn’t Make Mistakes: Harness Engineering for Non-DevelopersNanum Consulting corporate training · On-site / OnlineSee Course →
Need in-house training on this topic?
Get a curriculum and quote tailored to your needs right away.
Ask About Training
📚 See Related Course🗂 All Programs📄 Free Resources🔎 Glossary Home
Last updated 19 Oct 2026 · Reviewed by John Kim

FAQ

No. Even without terms of use, the Copyright Act limits what is allowed to the parts necessary for compatibility, and you cannot build a similar program from the information you obtain. Accessing a server without authorization during analysis may also trigger other laws.
Software is usually licensed, not owned, so even if you paid for it, the terms-of-use ban on reverse analysis applies. A program developed under outsourcing, where you received the rights or acceptance-inspection authority, can be analyzed depending on the contract terms.
Observing a public screen for ideas is not reverse analysis, and ideas themselves are not protected by copyright. But copying screen designs or wording outright can raise copyright or unfair competition issues.
A good starting point is: permitted targets (company-owned systems, deliverables you are authorized to inspect, security reviews), prohibited targets (products whose terms forbid it, copying competitors’ features), an approval process (prior legal review), and how results are stored.