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Japan web-system and app-backend data-leak wave

campaign · campaign:japan-web-system-data-leak-wave-2026-09

Run of personal-data leaks from Japanese internet-facing web systems and mobile-app backends since about September 2026 that JPCERT/CC (alert AT-2026-0030) groups into five attack cases: per-target scanning for known flaws, unauthorised calls to internal application APIs found by analysing the published app (NICT's app-to-backend attack), the Metabase SQL injection, JSP web shells placed as .war files, and AI penetration-testing platforms (Cairn, CyberStrikeAI, ARTEX). No actor is attributed (JPCERT/CC, NICT, 2026-10).

Aliases: JPCERT-AT-2026-0030, A2B attacks

Coverage
1
first 2026-10-26 → last 2026-10-26
Latest activity
2026-10-26
JPCERT/CC and NICT: attackers decompile the public app, then call internal APIs; AI platforms scan exposed…
Peak priority
notable
1 notable
Targets
·
regions: apac
Sources cited
4
4 hosts

Defender insights

What each entry about Japan web-system and app-backend data-leak wave tells a defender to do, newest first.

2026-10-26NOTABLEJPCERT/CC and NICT: attackers decompile the public app, then call internal APIs; AI platforms scan exposed web apps

Exposure · triage · detection

Story timeline

  1. 2026-10-26Japan's wave of personal-data theft from web systems: JPCERT/CC and NICT describe attackers who decompile the published Android app to find internal APIs, drop JSP web shells as .war files on application servers, and run AI penetration-testing platforms against exposed web applications and WSUS servers
    active-threatsJPCERT/CC and NICT: attackers decompile the public app, then call internal APIs; AI platforms scan exposed web apps

Hunting pivots

Tags
ai-abusedata-breachvulnerabilities
ATT&CK techniques (5 across 5 tactics)

5 techniques observed across 1 entry about this entity, derived from entry metadata and body evidence, never asserted without a published entry behind it · pinned to MITRE ATT&CK v20.0 · compare on the matrix · Navigator layer (JSON)

  • ReconnaissanceActive Scanning: Vulnerability Scanning
  • Initial AccessExploit Public-Facing Application
  • PersistenceServer Software Component: Web Shell
  • Credential AccessUnsecured Credentials: Credentials In Files
  • Command and ControlProxy: Multi-hop Proxy

Reconnaissance TA0043

T1595.002Active Scanning: Vulnerability Scanning×1

Adversaries may scan victims for vulnerabilities that can be used during targeting. Vulnerability scans typically check if the configuration of a target host/application (ex: software and version) potentially aligns with the target of a specific exploit the adversary may seek to use.

Evidence: 2026-10-26/jpcert-nict-app-to-backend-api-attacks-ai-scanning-japan · ATT&CK page ↗

Initial Access TA0001

T1190Exploit Public-Facing Application×1

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network. The weakness in the system can be a software bug, a temporary glitch, or a misconfiguration.

Evidence: 2026-10-26/jpcert-nict-app-to-backend-api-attacks-ai-scanning-japan · ATT&CK page ↗

Persistence TA0003

T1505.003Server Software Component: Web Shell×1

Adversaries may backdoor web servers with web shells to establish persistent access to systems. A Web shell is a Web script that is placed on an openly accessible Web server to allow an adversary to access the Web server as a gateway into a network. A Web shell may provide a set of functions to execute or a command-line interface on the system that hosts the Web server.

Evidence: 2026-10-26/jpcert-nict-app-to-backend-api-attacks-ai-scanning-japan · ATT&CK page ↗

Credential Access TA0006

T1552.001Unsecured Credentials: Credentials In Files×1

Adversaries may search local file systems and remote file shares for files containing insecurely stored credentials. These can be files created by users to store their own credentials, shared credential stores for a group of individuals, configuration files containing passwords for a system or service, or source code/binary files containing embedded passwords.

Evidence: 2026-10-26/jpcert-nict-app-to-backend-api-attacks-ai-scanning-japan · ATT&CK page ↗

Command and Control TA0011

T1090.003Proxy: Multi-hop Proxy×1

Adversaries may chain together multiple proxies to disguise the source of malicious traffic. Typically, a defender will be able to identify the last proxy traffic traversed before it enters their network; the defender may or may not be able to identify any previous proxies before the last-hop proxy. This technique makes identifying the original source of the malicious traffic even more difficult by requiring the defender to trace malicious traffic through several proxies to identify its source.

Evidence: 2026-10-26/jpcert-nict-app-to-backend-api-attacks-ai-scanning-japan · ATT&CK page ↗

Entries about Japan web-system and app-backend data-leak wave (1)

2026-10-26 · view entry permalink →

NOTABLENATOA2

Japan's wave of personal-data theft from web systems: JPCERT/CC and NICT describe attackers who decompile the published Android app to find internal APIs, drop JSP web shells as .war files on application servers, and run AI penetration-testing platforms against exposed web applications and WSUS servers

JPCERT/CC's alert of 2026-10-08, updated on 2026-10-23, says that around September 2026 Japanese organisations disclosed a run of personal-data leaks through unauthorised access, and singles out an attack type that may be increasing: systems the operator never expected strangers to reach, such as business-intelligence tools and staff-management systems, were hit alongside public apps (JPCERT/CC, 2026-10-23). It does not tie them to one method and groups them in five: per-target scanning for known flaws and exposed configuration and backup files; unauthorised calls to application management APIs; the Metabase SQL injection CVE-2026-72898; .war files carrying a JSP web shell that runs commands passed in query parameters, placed on application servers reachable from the public web server; and, added on 2026-10-23, attempts through AI penetration-testing platforms it names as Cairn, CyberStrikeAI and ARTEX, including against exposed WSUS servers (JPCERT/CC, 2026-10-23).

In the API case the attackers analyse the published smartphone app to find endpoints and keys, then attack internal APIs the app screens cannot reach: changing user rights, creating accounts, toggling a header or sending malformed tokens to compare responses, and blind NoSQL injection to find account data; some use API keys stolen elsewhere (JPCERT/CC, 2026-10-23). NICT calls this an app-to-backend attack: the app need not be vulnerable, and backend authentication, authorisation or input-validation faults leak data (NICT, 2026-10-13). On attack servers JPCERT/CC found Android packages, reverse-engineering tools and a Python script that answers requests with HTTP 302 redirects and appears to have been used to test for server-side request forgery (JPCERT/CC Eyes, 2026-10-21).

No source names an actor. JPCERT/CC says it confirmed that the attackers used AI to scan for known vulnerabilities and attack through APIs (JPCERT/CC Eyes, 2026-10-21), while Macnica could not confirm AI use (Recorded Future, 2026-10-22). API-attack access also arrives through Tor exit nodes and residential proxies (JPCERT/CC, 2026-10-23).

Triage: the app's own User-Agent proves nothing, because JPCERT/CC saw attack requests carrying it; the endpoints called and the sequence (header toggling, malformed tokens, role changes) discriminate, and a TLS fingerprint that matches a generic Python client does not identify the attacker alone (JPCERT/CC, 2026-10-23).

We confirmed that the attackers had used AI to scan for known vulnerabilities and carry out attacks via APIs.

One notable characteristic of these attacks was that the attackers analyzed Android application packages (APK files) to identify APIs and exploit them

JPCERT/CC Eyes

Macnica could not confirm the use of AI in these attacks.

Recorded Future Insikt Group 2026-10-22

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threat26 Oct 03:38Zmulti-sourceOpen finding →
Sources: JPCERT/CC (alert JPCERT-AT-2026-0030, updated 2026-10-23) · JPCERT/CC Eyes (attack infrastructure investigation) · NICT CYNEX (threat intelligence team LETTICE) · Recorded Future Insikt Group

Co-occurring entities

Derived: referenced by the same focused operational entries (weekly summaries and report roundups don't count); ×N counts the shared entries.

Where this entity is cited

  • Threats1

Source distribution

  • blogs.jpcert.or.jp1 (25%)
  • cynex.nict.go.jp1 (25%)
  • jpcert.or.jp1 (25%)
  • recordedfuture.com1 (25%)
All cited sources (4)