https://feed.craftedsignal.io/products/edgewebview/Trending threats, MITRE ATT&CK coverage, and detection metadata — refreshed continuously.Hugoenhello@craftedsignal.iohello@craftedsignal.ioWed, 03 Jan 2024 15:00:00 +0000https://feed.craftedsignal.io/briefs/2024-01-direct-syscall-process-access/Wed, 03 Jan 2024 15:00:00 +0000hello@craftedsignal.iohttps://feed.craftedsignal.io/briefs/2024-01-direct-syscall-process-access/Detects suspicious process access events where the call trace does not originate from known Windows system DLLs, indicating potential defense evasion by bypassing hooked APIs via direct syscalls.This detection identifies suspicious process access events on Windows systems where a process attempts to access another process’s memory via direct system calls, bypassing standard Windows API calls. Endpoint security solutions often hook userland Windows APIs to detect malicious code execution. Attackers can evade these hooks by directly invoking syscalls, which are lower-level instructions that interact directly with the operating system kernel. The rule specifically looks for process access events (Sysmon Event ID 10) where the call trace does not originate from known Windows system DLLs like ntdll.dll, indicating a potential attempt to bypass security measures. The rule excludes certain legitimate applications, such as Malwarebytes Anti-Exploit, Cisco AMP, Microsoft EdgeWebView, and Adobe Acrobat DC, to reduce false positives. This technique is often employed by advanced malware and red teams to evade detection.

Attack Chain

1. A malicious process is executed on the system, either through user interaction or exploitation of a vulnerability.
2. The process attempts to gain access to another process’s memory space (Target Process).
3. Instead of using standard Windows API calls, the malicious process directly invokes system calls (syscalls) to access the target process’s memory.
4. The CallTrace in the Sysmon event does not originate from expected system DLLs like ntdll.dll, sysfer.dll, wow64cpu.dll, wow64win.dll, or win32u.dll, indicating a direct syscall.
5. The process might attempt to read sensitive information such as credentials, inject malicious code, or manipulate the target process’s behavior.
6. The malicious process performs actions within the context of the target process, such as executing injected code or accessing sensitive data.
7. The attacker leverages the compromised process to achieve their objectives, such as data exfiltration, lateral movement, or privilege escalation.
8. The attacker cleans up any traces of their activity and attempts to maintain persistence on the compromised system.

Impact

Successful exploitation can lead to the compromise of sensitive data, the injection of malicious code into legitimate processes, and the complete takeover of the affected system. This can result in data breaches, financial loss, and reputational damage. The impact is especially significant if the target process holds sensitive credentials, browser secrets, or has security-product context.

Recommendation

• Enable Sysmon process access logging (Event ID 10) with call tracing and ingest the logs into your SIEM to activate the rules above (https://ela.st/sysmon-event-10-setup).
• Deploy the Sigma rules provided in this brief to your SIEM and tune them for your environment to detect direct syscall process access.
• Investigate any alerts generated by these rules, focusing on the SourceImage, TargetImage, GrantedAccess, and CallTrace fields in the Sysmon event to determine the legitimacy of the process access attempt.
• Prioritize investigation of alerts where the target process is lsass.exe or other security-sensitive processes.
• Implement robust endpoint detection and response (EDR) solutions to detect and prevent malicious activity on endpoints.
• Monitor for suspicious process creation events originating from the flagged processes.

]]>highadvisorydefense-evasionexecutionwindowshttps://feed.craftedsignal.io/briefs/2024-01-suspicious-process-calltrace/Wed, 03 Jan 2024 10:00:00 +0000hello@craftedsignal.iohttps://feed.craftedsignal.io/briefs/2024-01-suspicious-process-calltrace/The rule identifies suspicious process creation where a process is created and immediately accessed from an unknown memory code region by the same parent process, indicating a potential code injection attempt, specifically process hollowing, commonly targeting processes spawned by Microsoft Office applications, scripting engines, and command-line tools for defense evasion.This detection identifies potential process injection attempts, specifically process hollowing, by monitoring process creation events followed by memory access from unknown regions. The rule focuses on processes spawned by Microsoft Office applications (winword.exe, excel.exe, outlook.exe, powerpnt.exe), scripting engines (cscript.exe, wscript.exe, mshta.exe), and command-line tools (cmd.exe, powershell.exe, rundll32.exe, regsvr32.exe, wmic.exe, cmstp.exe, msxsl.exe). The logic looks for a spawned process by one of these applications/tools, followed by a process access event for an unknown memory region by the parent process, indicating a potential code injection attempt. Attackers use process injection to hide malicious activity within legitimate processes, evading detection and hindering forensic analysis. This technique is a common tactic used to establish persistence, escalate privileges, or execute malicious payloads.

Attack Chain

1. A user opens a malicious document or executes a script.
2. The Microsoft Office application (e.g., winword.exe) or scripting engine (e.g., wscript.exe) starts as a parent process.
3. The parent process creates a new child process (e.g., a legitimate system executable).
4. The attacker injects malicious code into the newly created child process’s memory, often overwriting legitimate code sections.
5. The parent process accesses the child process’s memory from an unknown code region, indicating the injected code. Sysmon event ID 10 captures this access.
6. The injected code executes within the context of the child process, performing malicious actions.
7. These actions can include establishing persistence, downloading additional malware, or exfiltrating data.

Impact

Successful process injection allows attackers to mask their malicious activities within legitimate processes, making detection and attribution significantly harder. This can lead to prolonged infections, data breaches, and system compromise. The impact can range from individual workstation compromise to widespread organizational damage, depending on the attacker’s objectives and the compromised system’s role. The rule mitigates risks associated with advanced persistent threats (APTs) and commodity malware using process injection for defense evasion.

Recommendation

• Enable Sysmon Event ID 1 (Process Creation) and Event ID 10 (Process Access) to collect the necessary telemetry for this detection (Sysmon Event ID 1 - Process Creation, Sysmon Event ID 10 - Process Access).
• Deploy the Sigma rule “Suspicious Process Creation CallTrace” to your SIEM and tune for your environment.
• Investigate any alerts triggered by the Sigma rule, focusing on the process execution chain and potential malicious activities performed by the injected code.
• Consider memory dumping the child process for further analysis, to examine if malicious code exists.

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