Detection of System Control Panel Item Load from Uncommon Locations

Attackers may use DLL sideloading or similar techniques to load malicious code through system control panel items (.cpl). This involves placing a malicious DLL in the same directory as a legitimate .cpl file (such as appwiz.cpl, bthprops.cpl, or hdwwiz.cpl) and tricking a legitimate application (like fondue.exe, fsquirt.exe, or hdwwiz.exe) into loading the malicious DLL instead of the intended one. This can lead to arbitrary code execution with elevated privileges, allowing the attacker to bypass security controls, persist on the system, or escalate privileges. The Sigma rule focuses on identifying .cpl files loading from outside standard system directories, offering a method to discover potential sideloading attempts. Defenders must monitor image load events for unusual .cpl loading to catch this type of activity.

Attack Chain

1. The attacker gains initial access to the system, potentially through phishing or exploiting a vulnerability.
2. The attacker drops a malicious DLL and a legitimate .cpl file (e.g., appwiz.cpl) into a non-system directory (e.g., C:\Users\Public).
3. A legitimate Windows application (e.g., fondue.exe) attempts to load the legitimate .cpl file.
4. Due to the presence of the malicious DLL in the same directory and Windows DLL search order, the malicious DLL is loaded instead of the legitimate one.
5. The malicious DLL executes arbitrary code, giving the attacker control within the context of the legitimate application.
6. The attacker leverages this control to perform actions such as installing malware, escalating privileges, or establishing persistence.
7. The attacker may use the compromised system as a pivot point to move laterally within the network.
8. The final objective is to achieve persistent access, exfiltrate sensitive data, or disrupt operations.

Impact

A successful DLL sideloading attack can grant the attacker complete control over the compromised system. This can result in data theft, system damage, or the deployment of ransomware. While the specific number of victims or sectors targeted is unknown in this instance, the potential impact is significant, especially on systems with sensitive data or critical functions. By bypassing security measures, attackers can maintain a persistent presence and conduct further malicious activities undetected.

Recommendation

• Deploy the provided Sigma rule to your SIEM and tune it for your environment to detect .cpl files loaded from unusual locations (logsource: image_load, category: windows).
• Investigate any alerts generated by the Sigma rule, focusing on processes loading .cpl files from non-standard paths.
• Implement application control policies to restrict the execution of binaries from untrusted locations to prevent sideloading attempts.
• Monitor process creation events for instances of fondue.exe, fsquirt.exe, or hdwwiz.exe loading .cpl files, as these are common targets for sideloading (logsource: process_creation, category: windows).