apk-reverse/references/ad-removal.md

Ad removal

Goal: ads stop appearing, and nothing else breaks. Read pitfalls.md P5 and P6 before patching anything here.

Step 1: enumerate what "ads" means in this app

Do not assume "ads" is one thing. Enumerate first.

SDK-integrated ads (the app calls an SDK):

• Search dex strings for SDK markers: openadsdk, TTAdSdk, TTAdNative, Pangle, pangolin, com.qq.e, GDTAd, gdt_plugin, anythink, ATSDK, ATRewardVideoAd, bdxadsdk, sigmob, ksad, mobads, beizi.
• Aggregators (AnyThink, TopOn, and similar) are wrappers: the ad networks underneath are their adapters, not app code. Patching an individual network's class is usually pointless; the aggregator still runs and still reaches the network.
• The app almost always funnels every call into one wrapper class. That class is the patch surface (Step 2).

Dynamic-plugin ad SDKs (the SDK is not in the APK). Aggregators increasingly ship as a runtime plugin: the app downloads an APK on first launch into its private directory and loads it through a plugin classloader.

/data/data/<app.package>/files/<sdk>_p/<plugin.pkg>/version-*/apk/base-1.apk
/data/data/<app.package>/files/<sdk>_p/<plugin.pkg>/version-*/lib/<abi>/*

• Consequence: deleting bundled assets/, lib/*.so, or the SDK's classes from the dex does not kill this SDK. The loader re-downloads on the next launch, and a half-deleted plugin is worse than an intact one.
• The kill switch is the init gate (Step 2). Killing init also prevents the working directory from ever being created, which is the strongest verification signal available (Step 4).
• The plugin may also be bundled. Two copies still means one init gate; patch that, not the payload.

Server-driven ads / sponsored content (the server returns the ad, the client renders it):

• Look for endpoints like /adverts, /adv, /banner, /config, and DTOs named Advertisement*, Advert*, Banner*, Promotion*.
• The client renders whatever the list contains. If the list is empty there is nothing to show, but see pitfalls.md P5 on how not to empty it.
• Sponsored cards that look like content (a VPN promo, a network-accelerator card, a third-party product) are usually exactly this.

Legit content that looks like an ad. Verify before acting. A /adverts?position=banner response containing anime titles and poster images is the home-page carousel, not an advertisement. Removing it removes real functionality.

Step 2: find the single convergence point

Almost every ad-enabled app wraps one SDK in a single singleton helper: init, loadSplash, loadBanner, loadFullScreen, loadReward all live in the same class. Find that class, and patch nothing else if you can.

helper.init(Application)              -> Sdk.init(appId, appKey); Sdk.start()   // plus plugin download
helper.showSplash(Activity, ViewGroup, onClose: () -> Unit)
helper.showInterstitial(Activity)
helper.showReward(Activity, onStart: () -> Unit, onFinish: (Boolean) -> Unit)
helper.preload*(Activity)
helper.canShow*(Activity): Boolean    // == isReady / isLoaded / isAdReady

Preferred play: readiness always false + init is a no-op.

1. Make the readiness predicate constant false (isReady / canShow* / isLoaded / isAdReady).
2. Make init an empty method (return-void) so the SDK never builds a network stack and never requests a plugin.
3. Only then touch show/load methods, and only for slots that bypass the readiness predicate.

Why this order works:

• Callers of a readiness predicate already own a "no ad available" branch, and the app ships and tests it. Returning false routes every slot through that existing path: no crash, no hang, no new code path.
• Killing init removes the SDK's network, cache, and download activity entirely. That is the difference between "the ad is hidden" and "the ad subsystem never started", and only the second claim is provable (Step 4).
• Per-slot patching (splash this week, interstitial next) leaves the SDK alive and downloading. Avoid it unless a slot ignores the predicate.

Method classification, once the helper is located:

Method	Contains	Patch
Init	Sdk.init(...) + Sdk.start(), plugin download	body -> return-void
Readiness / gate	isAdReady, canShow, isLoaded	return false / 0
Show splash / interstitial	constructs an ad object, loadAd() / show()	return-void, but preserve the completion callback
Show reward	same, plus success/failure lambdas	return-void; decide deliberately whether to grant the reward
Preload / warm-up	RewardVideoAutoAd.init(...), cache priming	return-void

The callback trap (this one breaks startup)

A splash/loading ad usually takes a completion lambda as a parameter, and the app's startup state machine waits for that lambda before dismissing the splash screen.

If you replace the method with a bare return-void, the lambda never fires and the app hangs on the splash screen forever. A patch that "removed the ad" and produced a frozen splash is this bug, not a repackaging bug.

Correct shape, skip the ad and still complete:

.method public final showSplash(Landroid/app/Activity;Landroid/view/ViewGroup;Lkotlin/jvm/functions/Function0;)V
    .registers N
    invoke-interface {p3}, Lkotlin/jvm/functions/Function0;->invoke()Ljava/lang/Object;
    return-void
.end method

Before patching, prove the contract. Read the listener class the method constructs and find which callback triggers the completion lambda (onAdDismiss? onAdError? onAdLoadTimeout?). That tells you whether to call it on success, on failure, or unconditionally.

For a reward ad whose lambdas are (onStart, (Boolean) -> Unit), granting the reward client-side is a choice: onFinish(true) makes the app treat the reward as earned. Check whether the reward is validated server-side before promising it.

Global timestamp gates (one write, many slots)

Some "free reading + ads" apps do not gate ads per slot. They store one local timestamp and every slot, cooldown, and interval check reads it: splash, chapter-break interstitial, unlock prompt, "next ad in N minutes". Patching call sites one by one always misses some.

• Find it: dump the app's preference keys and filter for ad-ish names (ad, free, cooldown, interval, end_time, expire, next_). Then hook SharedPreferences.getLong/getInt/getString and watch which key is read immediately before a slot appears. The key read across several screens is the gate.
• Patch it: in Application.onCreate(), write a far-future value as early as possible (for example 4102444800000L). Avoid Long.MAX_VALUE: implementations often compute end - now and can misjudge an extreme value. One write disables every reader at once, which is far more stable than editing each consumer.
• If the app overwrites it later: observe what it writes back under different start sequences. A single startup write is not automatically permanent for keys the app re-asserts; then patch the writer or the reader instead.
• Same technique, two key semantics: "ad-free until <date>" keys and "cooldown/interval" keys both respond to this, but the value differs. For a cooldown key, a far-future value means "next ad is never due", which is what you want, while a progress/check-in flow reading the same key may behave oddly.
• Side effects are mandatory in the delivery notes. The same key is often reused as a business field (the anchor for a new-user ad-free window, a remaining-quota counter). Forcing it to a far-future value changes those business judgements. Usually harmless for a de-ad goal, but state it explicitly and confirm the related screens do not show a broken state.
• With DataStore instead of SharedPreferences, a write inside Application.onCreate needs a coroutine or a blocking write; see runtime-data.md, and never block the main thread on persistence.

"Ads" vs ad-gating UI

Some blocking dialogs contain no ad slot at all ("watch an ad to unlock", skip/continue prompts, cooldown notices). If the goal is "the app is usable", they count as ads and must be handled too. Handle them by letting the gate pass, not by deleting the dialog view.

• Where the gate reads the timestamp key above, the timestamp patch already covers it.
• Where it reads a boolean or a canUnlock() method, patch that predicate.
• Business-coupled entrances need a check first. "Watch a video to earn benefits" may be a real feature. Decide with evidence: find the callers (scripts/find_refs.py) and see whether the entrance leads to a server request or a local entitlement write. A server-issued entitlement cannot be created client-side, so releasing the gate only fools the UI while the server still refuses; an entrance that changes purely local UI state is safe to release.

Step 3: choose the patch layer

From safest to riskiest (full technique table in dex-patching.md):

1. Kill SDK init (Step 2) — the SDK never starts; its networks, caches, and plugin downloads never happen. Highest-value single patch. Verify nothing else silently depended on init.
2. Neutralize the readiness gate — isReady/canShow return false; routes existing "no ad" branches.
3. No-op the show/preload methods — only when 1 and 2 are insufficient, always preserving callbacks.
4. Global gate state — one startup write covers every reader (timestamp / preference keys above).
5. Filter server-issued ad data at the consumption layer — drop entries for the target position before they reach UI state.
6. (avoid) Renderer-level suppression — only if the component is genuinely ad-exclusive. Check pitfalls.md P6 first.
7. (avoid) Transport-level blocking — see pitfalls.md P5.

Step 4: verify — three independent kinds of evidence

Logcat silence alone is weak evidence. A credible "ads are gone" claim needs all three, plus the neighbours:

1. UI, screen by screen — splash, home banner, detail page, reader/player, reward button, unlock prompt. Capture before/after screenshots (verification.md §screenshot discipline).
2. Logs — the SDK's characteristic tags are entirely absent, not merely quiet: anythink, ATSDK, Pangle, TTAd, GDT, ksad, and so on. Make this a count, not an impression. Aggregators log a recognisable burst while they probe which networks are wired in (a "SDK id N not integrated" style line, once per network). Capture the same fixed window on the original and on your build and compare numbers: 8 -> 0 is a measurement; "I did not see it" is not. A tag that goes quiet without reaching zero usually means the SDK still starts and simply failed to load an ad this run — a different, weaker result than "the subsystem never started".
3. Filesystem, the strongest signal — the app's private directory contains no ad SDK working directory at all:

   adb shell "su -c 'ls -la /data/data/<app.package>/files/'"
   

   For a dynamic-plugin SDK, an absent <sdk>_p tree proves the init gate never ran. It is not an artifact you can fake by hiding a view. If the tree exists, something still initializes the SDK: the init patch did not take effect, or a second init path exists.

Additional cheap evidence: 4. DNS / socket level — a runtime InetAddress hook. Before: a burst of ad/tracker domains. After: none. Many ad SDKs bypass the system proxy, so a proxy log can miss them while this does not. 5. Exercise the screens that had ads and confirm nothing unrelated regressed: images, playback, lists, pagination, downloads, login. 6. Clean install — uninstall first, then install. Data left from a previous run can hide a failed init patch (pitfalls.md P11).

Frame the result at the right strength: "the ad was hidden" vs "the ad subsystem never started". Only evidence 3 and 4 support the second (verification.md §the claim ladder).

Step 5: what is usually NOT removable

Be honest about residual ads rather than breaking the app to chase them:

• Server-driven content promos deep in a feature's own data payload, where the screen's load depends on the same request. Suppressing them requires a data-consumption patch, not transport blocking.
• Ads delivered as content (a sponsored "article" or a native card with no SDK marker) — indistinguishable from real content without runtime tracing.
• Ads whose SDK init also enables other features. Removing init can break functionality that silently depended on it. Verify before shipping; a working app with one residual ad beats a broken app.
• Server-issued entitlements gated behind watching an ad. The gate can be opened client-side, the entitlement cannot be created client-side.

If a residual ad cannot be removed without breaking something, say so, and say exactly which coupling caused it. That is a better deliverable than a broken APK.