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F5 Labs observes lone Russian IP scanning for SmarterMail CVE-2026-24423 unauthenticated RCE, a CISA KEV-listed flaw used in ransomware

1 fonte(s) · 1 atualização(ões) · publicado 12/03/2026 18:14 · coletado há 3 dias

F5 Labs analyzed exploitation of CVE-2026-24423, a CVSS 9.8 unauthenticated remote code execution flaw in SmarterTools SmarterMail (CWE-306). CISA added it to the KEV catalog on February 2, 2026 and notes it has been used in ransomware campaigns. Despite public write-ups, F5 sensors saw only one IP, 193.24.123.58 (ASN 200593, Russian ISP Prospero OOO), probing for it between February 17 and 22, 2026. That IP later moved on to scanning for CVE-2026-20128 (Cisco Catalyst SD-WAN Manager). The article also covers February 2026 trending CVEs, led by CVE-2017-9841 with over 85,000 exploit attempts.

6 exploits públicos

Há código de exploração publicado no Exploit-DB para CVE-2025-55182, CVE-2024-4577, CVE-2023-1389 e outros. O código não é reproduzido aqui: o link leva à fonte, e a explicação foi escrita pela IA a partir do arquivo publicado.

  1. exploit-db.com · EDB-52506 ↗ · aplicação web · multiple · pub. 09/04/2026 não verificado

    React Server 19.2.0 - Remote Code Execution

    The script targets CVE-2025-55182, a flaw in how React Server Components deserialize data sent to server function endpoints, as used by frameworks such as Next.js. An unauthenticated attacker with network access to an app running React 19.0.0 to 19.2.0 can trigger it with one crafted POST, no user interaction. It abuses object handling to run JavaScript on the server, giving command execution as the app user. It is a working-looking, blind PoC that scans a target list and leaks command output via DNS lookups; it only prints HTTP status.

    CVE-2025-55182 · autor: danieljavanrad · explicação gerada por IA
  2. exploit-db.com · EDB-52331 ↗ · aplicação web · php · pub. 15/06/2025 não verificado

    PHP CGI Module 8.3.4 - Remote Code Execution (RCE)

    This script exploits CVE-2024-4577, an argument injection flaw in PHP running as CGI on Windows, where a soft hyphen in the query string is turned into a dash and lets the attacker pass configuration options to the interpreter. It needs only network access to an exposed php-cgi executable, with no login or user interaction. The options make PHP run code sent in the request body, giving command execution as the web server user. It looks like a working exploit with multi-host scanning and an interactive shell.

    CVE-2024-4577 · autor: İbrahimsql · explicação gerada por IA
  3. exploit-db.com · EDB-51677 ↗ · remoto · hardware · pub. 10/08/2023 não verificado

    TP-Link Archer AX21 - Unauthenticated Command Injection

    This script exploits CVE-2023-1389, a command injection in the web interface of the TP-Link Archer AX21, where the country setting of the locale handler reaches a shell unsanitized. The attacker needs only network reach to the router's web interface, no login, and firmware older than 1.1.4 Build 20230219. Sending the crafted request twice runs commands as root, and here it opens a reverse shell to the attacker. It is a short but working proof of concept that matches the listed CVE.

    CVE-2023-1389 · autor: Voyag3r · explicação gerada por IA

Detalhes técnicos

  • The flaw sits in the SmarterMail API endpoint POST /api/v1/settings/sysadmin/connect-to-hub, which requires no authentication. The request carries JSON with hubAddress, oneTimePassword and nodeName.
  • The attacker points hubAddress at a server they control. That server returns a malicious response, for example a CommandMount value, which ends up in a shell command. This allows arbitrary command execution and file creation or writing.
  • The vulnerability was found by Cale Black (VulnCheck) and independently by watchTowr and CODE WHITE GmbH. SmarterTools patched it on January 15, 2026 in build 9511. The CVE was filed on January 22 and published by NVD the next day. Public disclosure came on January 26, 2026.
  • Observed activity from 193.24.123.58 began with GET /interface/app/authentication/login.html using Mozilla User-Agents, apparently to fingerprint SmarterMail. From February 20 it switched to the exploit POST using a python-requests User-Agent. F5 suggests two different tools were used.
  • The attacker hosted the fake hub on the same IP and rotated ports (17325, 17625, 17775, 18625, 18725, 18775). The hub was unresponsive when F5 checked, so the delivered payload is unknown.
  • About 30,000 SmarterMail instances appear in Shodan, mostly in the USA, followed by Malaysia. Some may be honeypots.
  • Other top CVEs for February 2026: CVE-2025-55182 (React Server Components deserialization, over 22,000 attempts), CVE-2024-4577, CVE-2019-9082, CVE-2022-47945 (over 2,200 attempts) and CVE-2023-1389.
  • ATT&CK: Exploit Public-Facing Application (T1190).

Remediação

  • Patch SmarterMail to build 9511 or later.
  • Restrict API access with a WAF and an allow-list of required URIs.
  • Monitor and filter outbound requests from API servers to arbitrary internet endpoints. This alone would have blocked the hub callback.
  • Scan for vulnerabilities aggressively and patch high-priority issues quickly.

Linha do tempo

  1. f5.com ↗ · pub. 12/03/2026 18:14 · coletado 19/10 18:02 primeiro registro

    F5 Labs observes lone Russian IP scanning for SmarterMail CVE-2026-24423 unauthenticated RCE, a CISA KEV-listed flaw used in ransomware

    ler a análise desta fonte

    F5 Labs analyzed exploitation of CVE-2026-24423, a CVSS 9.8 unauthenticated remote code execution flaw in SmarterTools SmarterMail (CWE-306). CISA added it to the KEV catalog on February 2, 2026 and notes it has been used in ransomware campaigns. Despite public write-ups, F5 sensors saw only one IP, 193.24.123.58 (ASN 200593, Russian ISP Prospero OOO), probing for it between February 17 and 22, 2026. That IP later moved on to scanning for CVE-2026-20128 (Cisco Catalyst SD-WAN Manager). The article also covers February 2026 trending CVEs, led by CVE-2017-9841 with over 85,000 exploit attempts.

    Technical Details

    • The flaw sits in the SmarterMail API endpoint POST /api/v1/settings/sysadmin/connect-to-hub, which requires no authentication. The request carries JSON with hubAddress, oneTimePassword and nodeName.
    • The attacker points hubAddress at a server they control. That server returns a malicious response, for example a CommandMount value, which ends up in a shell command. This allows arbitrary command execution and file creation or writing.
    • The vulnerability was found by Cale Black (VulnCheck) and independently by watchTowr and CODE WHITE GmbH. SmarterTools patched it on January 15, 2026 in build 9511. The CVE was filed on January 22 and published by NVD the next day. Public disclosure came on January 26, 2026.
    • Observed activity from 193.24.123.58 began with GET /interface/app/authentication/login.html using Mozilla User-Agents, apparently to fingerprint SmarterMail. From February 20 it switched to the exploit POST using a python-requests User-Agent. F5 suggests two different tools were used.
    • The attacker hosted the fake hub on the same IP and rotated ports (17325, 17625, 17775, 18625, 18725, 18775). The hub was unresponsive when F5 checked, so the delivered payload is unknown.
    • About 30,000 SmarterMail instances appear in Shodan, mostly in the USA, followed by Malaysia. Some may be honeypots.
    • Other top CVEs for February 2026: CVE-2025-55182 (React Server Components deserialization, over 22,000 attempts), CVE-2024-4577, CVE-2019-9082, CVE-2022-47945 (over 2,200 attempts) and CVE-2023-1389.
    • ATT&CK: Exploit Public-Facing Application (T1190).

    Remediation

    • Patch SmarterMail to build 9511 or later.
    • Restrict API access with a WAF and an allow-list of required URIs.
    • Monitor and filter outbound requests from API servers to arbitrary internet endpoints. This alone would have blocked the hub callback.
    • Scan for vulnerabilities aggressively and patch high-priority issues quickly.