Detect Incus Arbitrary File Read/Write via Malicious Image Template Symlink in Microsoft Sentinel
CVE-2026-48752 is a critical vulnerability (CVSS 9.9) in Incus (github.com/lxc/incus/v7/cmd/incusd) versions prior to 7.2.0. A malicious container image can include a crafted symlink within the templates/ directory that, when processed by incusd during image import or container creation, allows an attacker to read or write arbitrary files on the host filesystem. This constitutes a container escape primitive with host takeover potential. A public proof-of-concept exists.
MITRE ATT&CK
KQL Detection Query
union isfuzzy=true
(
SecurityEvent
| where EventID in (4663, 4656)
| where ObjectName matches regex @"(?i)(templates[\\/]|/var/lib/incus/|/var/snap/incus/)"
| where ObjectName matches regex @"(?i)(\.\./|\\\.\.\\)"
| project TimeGenerated, Computer, Account, ObjectName, ProcessName, EventID
),
(
AuditLogs
| where OperationName =~ "incusd"
| where ResultDescription has_any ("symlink", "templates", "path traversal")
| project TimeGenerated, OperationName, ResultDescription, InitiatedBy
),
(
Syslog
| where ProcessName =~ "incusd" or ProcessName =~ "incus"
| where SyslogMessage has_any ("templates/", "symlink", "path escape", "chroot", "container image")
| where SyslogMessage has_any ("error", "warn", "failed", "denied")
| project TimeGenerated, Computer, ProcessName, SyslogMessage, HostName
)
| extend AlertName = "CVE-2026-48752 - Incus Malicious Template Symlink"
| order by TimeGenerated descDetects suspicious file access patterns associated with CVE-2026-48752 exploitation — symlink traversal within Incus template directories and anomalous host file access by incusd. Covers Windows Security Events, Azure AD Audit Logs, and Linux Syslog sources.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate Incus image imports using templates with absolute paths that resolve correctly within the container rootfs
- Container management scripts that mount host directories explicitly for known administrative purposes
- Security scanning tools that intentionally test symlink resolution within container image stores
Other platforms for CVE-2026-48752
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Create Malicious Incus Image with Template Symlink Pointing to /etc/passwd
Expected signal: incusd process accessing /etc/passwd via symlink resolution from templates/ directory; auditd SYSCALL records for readlink/open by incusd PID targeting /etc/passwd
- Test 2Exploit Incus Template Symlink for Arbitrary Host File Write
Expected signal: incusd creating or writing to /tmp/incus-host-write-target via symlink from templates/; FileWriteInfo events for incusd outside container directories
- Test 3Scan Incus Image Store for Existing Malicious Template Symlinks
Expected signal: Read-only filesystem traversal of /var/lib/incus/images by the scanning shell process; no incusd involvement expected
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