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A flaw in Android's handling of a specially crafted short message can crash the smartphone's telephony service on delivery alone — dropping live calls, preventing new ones, and potentially blocking emergency dialling — without the victim ever seeing or touching the message.
The issue, dubbed the "SMS of Death" by the researchers behind the finding and described in a Security Affairs report, works by sending a manipulated SMS that the handset processes automatically as soon as it arrives. There is no link to tap, no attachment to open, and no notification to acknowledge: the crash happens in the background, and the message itself stays invisible to the user.
Availability, not espionage
What makes this bug worth attention is what it does not do. It steals nothing — no contacts, no messages, no credentials, no location. Instead it removes a phone's core function. The telephony service is the underlying component for all cellular voice connectivity on Android, so when it dies, everything built on top of it goes with it: ongoing calls are cut, incoming calls fail, and emergency numbers may become unreachable until the service recovers.
The outage is temporary, but that is part of the risk. A user whose phone suddenly cannot place a call is far more likely to suspect a carrier fault or a dead SIM than a malicious message sitting unread in the inbox — particularly because nothing on screen indicates an attack took place. In a genuine emergency, those few minutes of confusion matter.
Why SMS is the weak link
The attack also highlights a structural problem with SMS as a channel. Unlike an app install, a web link, or a permissions prompt, message delivery is not a user decision. SMS remains an auto-delivered, legacy protocol that operates largely outside the recipient's control, and it is reachable on every handset regardless of what software the user has installed. For an attacker, that makes a denial-of-service exploit of this kind exceptionally cheap to execute and difficult to trace back to a sender.
That asymmetry is worth weighing: high-profile espionage chains dominate mobile security coverage, but an availability attack that costs almost nothing to run, needs no victim cooperation, and can silence a phone remotely is arguably the more broadly felt threat.
What to do
Patches for Android security flaws are expected to arrive through the normal Android security update cycle, distributed by device manufacturers and carriers. Users should apply updates as soon as they are offered rather than deferring them.
For anyone who finds themselves unable to call immediately after receiving a message they never opened, the practical advice is simple: treat a sudden, unexplained loss of call capability as a possible security event, not just a network problem, and restart the device while checking for a pending update.
Given the scale of Android's installed base, this class of issue has a wide potential audience — which makes timely patching, rather than any single vendor's marketing claim, the most reliable defence available.
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Android 在處理一條經特別構造的短訊時存在缺陷，短訊一經送達即可令智能手機的電話服務崩潰——通話中斷、無法撥出新電話，甚至可能令緊急電話無法撥通——而受害者從未看過或碰過該則訊息。
有關問題由 Security Affairs 報道，發現該漏洞的研究人員將其命名為「死亡 SMS」（SMS of Death）。攻擊方式是發送一條經篡改的 SMS，手機一收到便會自動處理。收件人無需點擊任何連結、開啟任何附件或確認任何通知：崩潰在背景發生，訊息本身對用戶保持隱形。
目標是中斷服務，而非間諜活動
這個漏洞值得關注之處，在於它「沒有做」的事。它不竊取任何東西——沒有聯絡人、沒有訊息、沒有登入憑證、沒有位置資料。相反，它移除的是手機的核心功能。電話服務是 Android 上所有流動語音通訊的底層組件，一旦它失效，建立於其上的一切都會隨之消失：通話中的對話被切斷、來電無法接通，緊急號碼在服務恢復前亦可能無法撥通。
服務中斷只是暫時的，但這正是風險所在。用戶的手機突然無法撥打電話，比起懷疑收件箱內一封未讀的惡意訊息，更可能認為是電訊商故障或 SIM 卡失效——尤其因為螢幕上完全沒有跡象顯示曾遭受攻擊。在真正緊急的情況下，這幾分鐘的混亂可能至關重要。
為何 SMS 是最薄弱的一環
是次攻擊同時突顯了 SMS 作為傳輸渠道的結構性問題。與安裝應用程式、點擊網頁連結或授權權限提示不同，訊息送達並非由用戶決定。SMS 至今仍是一種自動送達的舊式協議，運作方式基本上不受收件人控制，而且無論用戶安裝了什麼軟件，每一部手機都能接收。對攻擊者而言，這類拒絕服務（denial-of-service）漏洞利用的成本異常低廉，且難以追溯至發送者。
這種不對稱值得權衡：高調的間諜攻擊鏈主導了手機保安的報導篇幅，但一場幾乎零成本、無需受害者配合、即可遙距令手機失聲的可用性攻擊，可算是影響更廣泛的威脅。
應如何應對
Android 安全漏洞的修補程式預計會透過正常的 Android 安全更新週期送達，由設備製造商及電訊商分發。用戶應在收到更新時立即套用，而非延遲。
如果收到一則從未開啟的訊息後隨即無法撥打電話，實用的建議很簡單：把突如其來、原因不明的通話功能喪失視為可能的保安事件，而不只是網絡問題，同時重啟設備並檢查是否有待安裝的更新。
鑑於 Android 裝機量的規模，這類問題的潛在受眾相當廣泛——因此，及時套用修補程式，而非依賴任何單一廠商的市場宣傳，才是現時最可靠的防禦手段。