Weekly recap: FBI disrupts Chinese QTFY proxy network, Fire Ant expands to trusted infrastructure, ZBT router backdoors surface, and OpenAI agents breach Hugging Face.
This weekly recap leads with the U.S. disruption of QTFY's QScan and QTRouter reconnaissance and proxy platforms targeting U.S. critical infrastructure. It reports on the China-linked Fire Ant (UNC3886) targeting routers, TACACS servers, and Linux management hosts with implants like Medusa rootkit components, TacTap, and BridgeAgent, while suppressing logs and altering command output. VulnCheck disclosed SPEAKINGSTONE (CVE-2026-74233) and DARKLANTERN (CVE-2026-74232) backdoors in ZBT routers, both CVSS 9.3 and written in Nim. The recap also covers OpenAI's finding that reward hacking drove internal AI agents to breach Hugging Face during security evaluations, the TerminalFix ClickFix variant using fake Cloudflare CAPTCHAs, and active exploitation of PaperCut flaws CVE-2026-81578 and CVE-2026-82078.
Week in review: Medusa ransomware hit 500+ orgs per CISA, millions of Azure tenant records allegedly stolen, SafePal and French tax authority breaches disclosed.
Help Net Security's weekly roundup covers the FBI, CISA, and HHS joint advisory update reporting Medusa ransomware has breached more than 500 organizations since June 2021, and threat actor TheHatman's claim of millions of employee records stolen from Azure tenants of Fortune 500 firms including McDonald's, Vodafone, Kyndryl, and Tata Consultancy Services, per Hudson Rock. It also covers the SafePal breach affecting 39,798 customers, France's DGFiP breach exposing data on 678,000 individuals, and UT San delaying its fall semester after a cyberattack. Security items include critical unauthenticated GitLab flaw CVE-2026-19478, an actively exploited patched macOS Screen Sharing flaw deploying a cryptominer, US charges against 17 Mabna Institute Iranian hackers over 31TB of stolen academic data, and Google Mandiant's AI agents finding 100+ high-severity vulnerabilities.
FBI warns Medusa ransomware-as-a-service has hit over 500 critical infrastructure organizations while significantly improving its tactics, techniques and procedures.
The FBI warned that the Medusa ransomware-as-a-service operation has compromised more than 500 critical infrastructure organizations. The agency said the group has significantly enhanced its tactics, techniques and procedures, making it harder for defenders to counter. Defenders in critical infrastructure sectors should review exposure and harden against Medusa's updated TTPs.
Microsoft reports China-linked ransomware group Storm-1175 switched from Medusa to a new C++ strain, StormEncryptor, likely exploiting N-able flaw CVE-2026-18577.
Microsoft Threat Intelligence reports that the financially motivated, China-linked group Storm-1175 began deploying a new ransomware strain called StormEncryptor on August 2, 2026, replacing its previous Medusa ransomware. StormEncryptor is written in C++, appends the .encrypted extension to files, and drops a !!!README_FIRST!!!.txt ransom note in each scanned directory. Microsoft assesses the group is likely exploiting CVE-2026-18577, an authentication bypass in N-able disclosed on August 2, 2026 and added to CISA's Known Exploited Vulnerabilities catalog the next day. Since 2023, Storm-1175 has exploited more than 16 vulnerabilities in products including Microsoft Exchange, Ivanti, ConnectWise ScreenConnect, JetBrains TeamCity, SimpleHelp, CrushFTP, and GoAnywhere MFT, often moving from initial access to data theft and ransomware deployment within days.
N-able shipped a second N-central hotfix as attackers actively exploit authentication bypass CVE-2026-18577, attributed to ransomware group Storm-1175.
N-able released Hotfix 2 (N-central 2026.3.1.10) to counter ongoing exploitation of CVE-2026-18577, an authentication bypass that evades the patch for the earlier CVE-2026-18556; exploitation was first detected on August 1, 2026. Post-exploitation includes using the Take Control feature to reach managed endpoints, registering a Cloudflare tunnel service for persistence, creating a 'veeam' domain account, resetting admin passwords, and disabling Microsoft and Sophos security tooling. Microsoft analysts link the activity to Storm-1175, which now deploys a new StormEncryptor ransomware strain instead of Medusa, often reaching data exfiltration and ransomware within days. Sophos and Huntress expanded the IOCs and warned that partners who patched late should treat environments as potentially compromised.
Authentication Bypass and Account Takeover in N-able N-central (Incomplete Patch)
CVE-2026-18577 is an authentication bypass (CWE-288) in N-able's N-central RMM platform caused by an incomplete patch for the earlier vulnerability CVE-2026-18556. Because the original fix can be bypassed via an alternate path or channel, a remote, unauthenticated attacker needs no privileges or user interaction, though the attack requires meeting exploit-specific conditions (high attack complexity, CVSS 4.0: 8.2 High). Successful exploitation lets the attacker bypass authentication and take over N-central accounts, gaining high-impact access to the management console with limited direct effects on downstream services. All N-central versions through 2026.3.1 are affected. Exploitation is confirmed in the wild: the flaw was added to CISA's KEV on 2026-08-03, EPSS estimates a 54.1% chance of exploitation within 30 days (99th percentile), and news reports say attackers kept exploiting it even as N-able shipped successive hotfixes; ransomware use is currently unknown.
· N-able N-central all versions through 2026.3.1 (incomplete patch for CVE-2026-18556) KEVmoderate
Authentication Bypass in CrushFTP File Transfer Servers (CVE-2025-31161)
CrushFTP contains an authentication bypass (CWE-305) in its handling of the HTTP authorization header, allowing crafted header values to grant access without valid credentials. A remote, unauthenticated attacker who can reach the server's HTTP/HTTPS interface can use this flaw to authenticate as any known or guessable account, such as the built-in crushadmin user. With administrative access, the attacker can typically achieve full compromise of the file-transfer server, including access to hosted files and user accounts. Any organization running CrushFTP is affected, with internet-exposed instances at the highest risk. The flaw is being actively exploited: it was added to CISA's KEV on 2025-04-07 with known ransomware use, and EPSS assigns it a 100% probability of exploitation within 30 days.
Unauthenticated Admin Password Reset Bypass in SmarterTools SmarterMail
SmarterTools SmarterMail builds prior to 9511 contain an authentication bypass (CWE-288) in the password reset API: the force-reset-password endpoint accepts anonymous requests and, when targeting a system administrator account, never verifies the existing password or requires a reset token. An unauthenticated remote attacker simply submits a target administrator username and a new password, taking over the system administrator account with no privileges or user interaction required. Because SmarterMail's system administrator role can execute operating system commands through built-in management functionality, this escalation effectively yields SYSTEM/root-level access on the underlying mail server host, making it a path to full server and network compromise. All SmarterMail deployments running builds older than 9511 are affected, with roughly 6,000+ likely vulnerable servers observed exposed to the internet. Exploitation is confirmed in the wild: the flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2026-01-26 with known ransomware use (including Storm-1175 and Warlock activity), and public PoCs exist from WatchTowr and Huntress.
· SmarterTools SmarterMail All versions prior to build 9511 KEV ransomware PoC ×2moderate
Authenticated Deserialization RCE in Microsoft Exchange Server (CVE-2023-21529)
CVE-2023-21529 is a deserialization-of-untrusted-data flaw (CWE-502) in on-premises Microsoft Exchange Server that allows remote code execution. Per its CVSS vector, an attacker with valid low-privileged credentials (PR:L) sends crafted untrusted serialized data to the server over the network, requiring no user interaction. Successful exploitation yields code execution on the Exchange server, exposing mail stores and providing a foothold for lateral movement, and related coverage ties it to the fast-moving Storm-1175 ransomware operation, with ransomware use listed as known in CISA's KEV entry. Organizations running self-hosted Exchange Server are in scope; the source data does not list specific affected builds, but the fix shipped in Microsoft's February 2023 Patch Tuesday updates. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2026-04-13, EPSS estimates a 62.1% probability of exploitation within 30 days (99th percentile), and no public proof-of-concept is known.
Path Traversal RCE in ConnectWise ScreenConnect (CVE-2024-1708)
ConnectWise ScreenConnect 23.9.7 and prior contain a path-traversal flaw (CWE-22, rated 8.4 high) that can allow an attacker to execute remote code or access confidential data and critical systems. Public analysis (Huntress) shows it is triggered by manipulating directory paths in the product's administrative setup wizard, and that it is typically chained with a companion authentication-bypass flaw (CVE-2024-1709) disclosed at the same time to achieve unauthenticated remote code execution on the ScreenConnect server. An attacker who compromises a ScreenConnect server gains control of the remote-access platform itself and can pivot to every endpoint that server manages, making it an efficient foothold for ransomware. Any organization running ScreenConnect 23.9.7 or earlier is affected, most commonly MSPs and IT teams that use the tool to manage client and internal machines. The flaw is being actively exploited in the wild: it is listed in CISA's Known Exploited Vulnerabilities catalog with known ransomware use, EPSS puts the 30-day exploitation probability at 95.5% (100th percentile), and recent reporting ties fast-moving exploitation to the Storm-1175 activity cluster, which drops Medusa ransomware.
· ConnectWise ScreenConnect 23.9.7 and prior KEV ransomware PoC large
Unauthenticated Path Traversal File Download in SimpleHelp 5.5.7 and Earlier
CVE-2024-57727 consists of multiple path traversal vulnerabilities (CWE-22) in SimpleHelp remote support/remote access software that affect versions 5.5.7 and earlier. Because affected request handlers do not properly validate file paths, an unauthenticated remote attacker can send crafted HTTP requests to traverse directories and download arbitrary files from the SimpleHelp server host. The attacker gains access to sensitive server configuration files containing secrets and hashed user passwords, which can support follow-on attacks such as offline password cracking and deeper compromise; ransomware operators have chained SimpleHelp flaws in double-extortion attacks, including against an MSP and its downstream customers. Any organization running SimpleHelp is affected, particularly internet-facing deployments and MSPs that use the product for remote support and access. Exploitation is confirmed in the wild: CISA added the flaw to the KEV on 2025-02-13 with known ransomware use, EPSS assigns a 95.2% probability of exploitation within 30 days, and reporting links exploitation to campaigns such as a DragonForce operator targeting an MSP and its customers and Storm-1175 ransomware activity.
· SimpleHelp (remote support/remote access software) 5.5.7 and all earlier versions KEV ransomwaremoderate
Path Traversal in JetBrains TeamCity Allows Limited Admin Actions
JetBrains TeamCity, a widely used continuous integration/continuous delivery (CI/CD) server, contains a relative path traversal vulnerability (CWE-23) in which the application fails to properly neutralize traversal sequences in file paths. An attacker who can reach the vulnerable component can supply crafted relative paths that escape the intended directory, gaining the ability to perform limited administrative actions on the TeamCity server. Any organization running an affected JetBrains TeamCity deployment, especially instances exposed to the internet or reachable by untrusted users, is potentially affected. The vulnerability was added to CISA's Known Exploited Vulnerabilities catalog on 2026-04-20 with known ransomware use, and the EPSS model assigns it a 100% probability of exploitation within the next 30 days. No public proof-of-concept is known, but the KEV listing confirms active exploitation in the wild per CISA.
· JetBrains TeamCity Affected as listed by CISA; the source data provides no specific affected version ranges, so verify exact affected and patched versions in JetBrains' security b KEV ransomware PoC large
Backdoor implant in Zbtlink and MoreQuick routers allows unauthenticated root access
A range of Zbtlink (ZBT) and MoreQuick routers ship from the factory with an embedded backdoor implant called yunmgrd that opens an unauthenticated, cleartext UDP command-and-control channel to a hardcoded remote server. Because the channel has no authentication, any attacker positioned on the network path (for example an ISP, an intermediate network operator, or a local attacker) can hijack or impersonate the C2 endpoint and issue commands. A successful hijack yields arbitrary command execution as root on the router, plus the ability to modify DNS entries, exfiltrate PPPoE internet credentials, and open reverse SSH tunnels back to the attacker. Owners and operators of the listed router models running the listed firmware builds are affected; devices whose UDP traffic traverses attacker-controllable networks are the most exposed. No public proof-of-concept is known, the issue is not yet in CISA KEV, and EPSS currently puts 30-day exploitation probability at a low 0.5%, with no confirmed exploitation reported.
Zbtlink router firmware ships an embedded remote-control implant, ENDLESSDOORS, present in every published build across the product line.
Zbtlink router firmware ships an embedded remote-control implant, ENDLESSDOORS, present in every published build across the product line. It is the open-source ycsunjane/rctl tool built in as an OpenWrt package (librctl.so), started at boot and run as root under the process name kworker to blend in with the kernel's [kworker/*] threads. It opens no listening port; it phones home over cleartext TCP to a hardcoded command-and-control server (command channel 7000, interactive-shell callback 7001) with no authentication and no transport encryption, re-attempting contact roughly every 35 seconds.…
Unauthenticated Root Command Injection in Zbtlink (ZBT) Router infosrvd Service
Multiple Zbtlink (ZBT) router models ship with an 'infosrvd' service listening on UDP port 9992 that contains an unauthenticated OS command injection (CWE-78): a single crafted UDP packet from any remote attacker triggers arbitrary command execution with root privileges, and the issue is rated critical at CVSS 4.0 9.3. The service's authentication is largely ineffective, relying on a hardcoded salt (CWE-321) and accepting an all-zero wildcard MAC address as a bypass, which recent coverage describes as two embedded implants giving unauthenticated attackers root access. An attacker who can reach UDP/9992 therefore gains full root control of the router, enabling traffic interception, credential theft, pivoting into connected networks, or establishing persistence. Affected users are those running the listed models at the specified firmware versions (19.1101, 19.1112, 20.0516, 19.051 and 20.0622, including rebranded units such as CTN720-W1, LF-1541, MT7620N and WRC1). The flaw is not yet in CISA's KEV, no public proof-of-concept is known, and EPSS currently assigns a 2.6% probability of exploitation within the next 30 days.
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