Carbon.exe is an RAR-archived executable that acts as a dropper for the Monero miner XMRig. Carbon has been observed being downloaded and executed via PowerShell Invoke-Expression payloads in common remote code execution (RCE) attacks. The dropper contains a PowerShell script named SchTask.ps1 that is used in multiple stages of the killchain.
- The attacker exploits an attack vector on the vulnerable server and achieves RCE. The attacker also executes a PowerShell command.
- The server executes the attacker’s command and PowerShell sends an HTTP GET request to the attacker and successfully downloads ‘win.txt’.
- PowerShell invokes ‘win.txt’ and sends an HTTP GET request to the attacker’s server and successfully downloads ‘carbon.exe’ before unpacking and executing the XMRig miner.
- The installed XMR miner XMRig sends results to a mining pool server.
The attacker must be able to send crafted packets to the target system.
Alert Logic Coverage
Alert Logic® has evaluated its customer base for exposure to the exploit and has developed signatures for mitigating the threat depending on the security service in place.
The Network-Based Intrusion Detection System (IDS) has been updated with the new signatures for this exploit when detected via Alert Logic Threat Manager™. If this signature is detected, an incident is generated in the Alert Logic console.
Detection of this threat is provided via the Alert Logic ActiveWatch for Log Manager™ service. Log messages are produced by the vulnerable system when an exploit of this type is leveraged. An incident will be generated in the Alert Logic console if these log messages are observed.
Recommendations for Mitigation
Upgrade to a non-vulnerable version to mitigate this vulnerability.