A ransomware gang exploited the crucial React2Shell vulnerability (CVE-2025-55182) to realize preliminary entry to company networks and deployed the file-encrypting malware lower than a minute later.
React2Shell is an insecure deserialization problem within the React Server Parts (RSC) ‘Flight’ protocol utilized by the React library and the Subsequent.js framework. It may be exploited remotely with out authentication to execute JavaScript code within the server’s context.
Inside hours of its disclosure, nation-state hackers began to use it in cyberespionage operations or to deploy new EtherRAT malware. Cybercriminals have been additionally fast to leverage it in cryptocurrency mining assaults.
Nonetheless, researchers at company intelligence and cybersecurity firm S-RM noticed React2Shell being utilized in an assault on December 5 by a menace actor that deployed the Weaxor ransomware pressure.
Weaxor ransomware assault
Weaxor ransomware appeared in late 2024 and is believed to be a rebrand of the Mallox/FARGO operation (often known as ‘TargetCompany’) that targeted on compromising MS-SQL servers.
Like Mallox, Weaxor is a much less refined operation that targets public-facing servers with opportunistic assaults demanding comparatively low ransoms.
The operation doesn’t have an information leak portal for double extortion, and there’s no indication that it performs knowledge exfiltration earlier than the encryption part.
S-RM researchers say that the menace actor deployed the encryptor shortly after gaining preliminary entry by React2Shell. Whereas this implies an automatic assault, the researchers didn’t discover any proof within the compromised setting to assist the idea.
Instantly after the breach, the hackers executed an obfuscated PowerShell command that deployed a Cobalt Strike beacon for command and management (C2) communication.
Within the subsequent step, the attacker disabled real-time safety in Home windows Defender and launched the ransomware payload. All this occurred in lower than a minute for the reason that preliminary entry stage.
In keeping with the researchers, the assault was restricted to the endpoint that was susceptible to React2Shell, as they didn’t observe any lateral motion exercise.
After encryption, the information had the ‘.WEAX’ extension, and each impacted listing had a ransom word file named ‘RECOVERY INFORMATION.txt’, which contained fee directions from the attacker.
S-RM says that Weaxor additionally wiped quantity shadow copies to forestall simple restoration and cleared occasion logs to make forensic evaluation extra tough.
Notably, the researchers report that the identical host was subsequently compromised by different attackers utilizing completely different payloads, which is indicative of the extent of malicious exercise round React2Shell.
S-RM means that system directors evaluation Home windows occasion logs and EDR telemetry for any proof of course of creation from binaries associated to Node or React, as patching alone isn’t sufficient.
Course of spawning of cmd.exe or powershell.exe from node.exe is a robust indicator of React2Shell exploitation Uncommon outbound connections, disabled safety options, log clearing, and useful resource spikes also needs to be completely investigated.
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