{
  "family": "archsms",
  "sample_count": 127,
  "category": "ransomware",
  "description": "Trojan:Win32/Archsms is a malicious payload historically associated with toll fraud, designed to stealthily subscribe infected endpoints (often mobile devices synced with PCs or via modem hijacking) to premium-rate SMS services, draining the victim's funds.<br><br><b>Understanding Archsms</b><br>To the victim, the infection is often only discovered when reviewing their monthly cellular or internet bill and noticing massive, unauthorized charges. For security analysts, Archsms represents a direct monetization threat. Before the prevalence of ransomware, toll fraud via premium SMS was a primary method for cybercriminals to extract immediate financial value from an infection.<br><br><b>Execution and Evasion Strategies</b><br>Archsms is typically distributed via fake software installers, malicious mobile applications (sideloaded via USB from an infected PC), or through browser exploit kits targeting legacy modem configurations. Once executed, the trojan operates silently. It accesses the device's messaging APIs or connected dial-up modems and begins sending SMS messages to premium-rate numbers owned by the attackers. To evade detection, Archsms often intercepts and deletes the confirmation or 'receipt' SMS messages sent back by the telecom provider, keeping the user entirely unaware of the ongoing fraud.<br><br><b>Indicators of Compromise & Impact</b><br>The impact is direct financial loss. Incident responders investigating historical PC infections might find Archsms attempting to interface with connected mobile devices (via ADB or synchronization software) or attempting to dial out using legacy AT commands if a modem is present. The presence of anomalous, hidden logs detailing SMS transmission success rates in the <code>%AppData%</code> directory is a strong IoC.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1115",
    "T1582",
    "T1204.002",
    "T1562.001",
    "T1547.001"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1582",
      "name": "SMS Routing",
      "tactic": "Collection"
    },
    {
      "id": "T1115",
      "name": "Clipboard Data",
      "tactic": "Collection"
    },
    {
      "id": "T1562.001",
      "name": "Impair Defenses: Disable or Modify Tools",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1204.002",
      "name": "User Execution: Malicious File",
      "tactic": "Execution"
    },
    {
      "id": "T1547.001",
      "name": "Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder",
      "tactic": "Persistence"
    }
  ],
  "containment_steps": [
    "Immediately disconnect any synced mobile devices from the infected endpoint and review the device for unauthorized, sideloaded applications.",
    "Advise the victim to contact their telecom provider immediately to dispute the premium charges and place a hard block on premium SMS services.",
    "Utilize an EDR or comprehensive AV scan to locate and terminate the Archsms executable running from the user's profile directory.",
    "Ensure that any legacy dial-up modems connected to the endpoint are physically disconnected or disabled in the Device Manager."
  ],
  "what_to_avoid": [
    "Do not ignore the infection as a 'mobile only' problem; PC-based variants actively bridge the gap to infect connected devices.",
    "Avoid assuming the charges will stop by simply rebooting; the trojan establishes persistent Run keys to continue the fraud indefinitely."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}