CVE-2026-106931: EG Secure Solutions SiteGuard Server Edition OS Command Injection

Overview

CVE-2026-106931 identifies an OS command injection vulnerability within EG Secure Solutions SiteGuard Server Edition. This flaw enables a local attacker with low privileges to execute arbitrary operating system commands with elevated root or SYSTEM privileges. The vulnerability is critical due to its potential for full system compromise and is listed in CISA’s Known Exploited Vulnerabilities Catalog.

Technical Analysis

EG Secure Solutions SiteGuard Server Edition is susceptible to an OS command injection vulnerability (CWE-78). A local attacker with low privileges can leverage this flaw to inject and execute arbitrary OS commands. The successful execution of these commands occurs with the privileges of the affected product, which are root or SYSTEM. The CVSS 3.0 score is 7.8 (HIGH), with a vector of CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, indicating a local attack vector requiring low privileges, with high impact on confidentiality, integrity, and availability.

• Vulnerability Type: OS Command Injection (CWE-78)
• Affected Product: EG Secure Solutions SiteGuard Server Edition
• Attack Vector: Local (AV:L)
• Privileges Required: Low (PR:L)
• Impact: Arbitrary OS command execution with root or SYSTEM privileges, leading to high impact on confidentiality, integrity, and availability.
• Affected Versions: Specific affected versions are not detailed in the provided source material, but the vulnerability affects SiteGuard Server Edition.

Detection

Detection efforts should focus on identifying unusual process execution patterns originating from the SiteGuard Server Edition process, particularly the spawning of shell interpreters or system utilities.

• Monitor process creation events for SiteGuard Server Edition (or its associated executable) spawning suspicious child processes like cmd.exe, powershell.exe, sh, bash, python, perl, or other scripting interpreters.
• Look for command-line arguments passed to these child processes that indicate system modification, privilege escalation attempts, or data exfiltration.
• Analyze web server logs (if SiteGuard has a web interface) for unusual or malformed requests that could trigger command injection, especially in parameters known to be processed by the application.
• Review system logs for unexpected changes to critical system files, user accounts, or service configurations that might follow successful exploitation.

Sigma Detection Rules

SiteGuard Server Edition Spawning Windows Shell

title: SiteGuard Server Edition Spawning Windows Shell
id: 934d6731-a1b2-4c3e-8d5f-e2f0a1b2c3d4
status: experimental
description: Detects SiteGuard Server Edition spawning cmd.exe or powershell.exe, indicative of OS command injection exploitation.
logsource:
  product: windows
  service: sysmon
detection:
  selection:
    EventID: 1
    ParentImage|contains: 'SiteGuard'
    Image|endswith:
      - '\\cmd.exe'
      - '\\powershell.exe'
  condition: selection
level: high

SiteGuard Server Edition Spawning Linux Shell

title: SiteGuard Server Edition Spawning Linux Shell
id: 5e6f7a8b-c9d0-1e2f-3a4b-5c6d7e8f9a0b
status: experimental
description: Detects SiteGuard Server Edition spawning common Linux shells, indicative of OS command injection exploitation.
logsource:
  product: linux
  service: auditd
detection:
  selection:
    type: 'EXECVE'
    a0|contains: 'SiteGuard'
    a1|endswith:
      - '/bin/sh'
      - '/bin/bash'
      - '/bin/dash'
      - '/bin/zsh'
  condition: selection
level: high

Mitigations

1. Patch Immediately: Apply all available security updates and patches from EG Secure Solutions for SiteGuard Server Edition. Refer to the vendor’s security advisories for specific patch information.
2. Least Privilege: Ensure that the SiteGuard Server Edition service runs with the absolute minimum necessary privileges. If possible, restrict its ability to spawn new processes or execute arbitrary commands.
3. Network Segmentation: Isolate systems running SiteGuard Server Edition on a dedicated network segment to limit potential lateral movement if compromised.
4. Endpoint Detection and Response (EDR): Deploy and configure EDR solutions to monitor for and block suspicious process creation and command execution originating from the SiteGuard Server Edition process.
5. Input Validation: While a vendor fix is paramount, ensure that any custom integrations or scripts interacting with SiteGuard Server Edition implement robust input validation to prevent similar injection flaws.

References

• https://nvd.nist.gov/vuln/detail/CVE-2026-106931
• https://jvn.jp/en/jp/JVN88474777/
• https://www.eg-secure.co.jp/siteguard/news/alert-202610-1
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-106931
• https://ltna.com.au/cyber

Indicators of Compromise

No public IOCs available at time of writing.

MITRE ATT&CK

• T1059 — Command and Scripting Interpreter
• T1059.003 — Windows Command Shell
• T1059.004 — Unix Shell