CVE-2026-79298: Howyar SysReturn Arbitrary Code Execution

CVE-2026-79298 Overview

CVE-2026-79298 affects Howyar Technologies SysReturn versions prior to 11.3.034. A local attacker can execute arbitrary code by leveraging the BOOTia32.efi bootloader together with a crafted cloak32.dat file placed on the EFI System Partition (ESP). The flaw resides in the pre-boot Unified Extensible Firmware Interface (UEFI) execution path, giving an attacker code execution before the operating system loads. Howyar addressed the issue in version v.11.3.0.34. The vulnerability falls under the BIOS/UEFI and Bootloader class, with implications for Secure Boot integrity when vulnerable modules remain trusted in the boot chain.

Critical Impact

Arbitrary code execution at the UEFI stage enables persistent, pre-OS compromise that survives operating system reinstalls.

Affected Products

• Howyar Technologies SysReturn versions prior to 11.3.034
• Systems using the vulnerable BOOTia32.efi UEFI bootloader
• Endpoints with a writable ESP containing cloak32.dat

Discovery Timeline

• 2026-09-16 - CVE-2026-79298 published to the National Vulnerability Database (NVD)
• 2026-09-16 - Last updated in NVD database

Technical Details for CVE-2026-79298

Vulnerability Analysis

The vulnerability exists in Howyar SysReturn's UEFI boot component BOOTia32.efi. During early boot, the module reads and processes cloak32.dat from the ESP without adequate validation. An attacker who can write a crafted cloak32.dat file to the ESP influences execution flow within the signed UEFI application. This yields arbitrary code execution in the pre-boot environment. Because BOOTia32.efi may be trusted by Secure Boot, the flaw can be abused to bypass boot integrity controls. Public technical analysis and proof-of-concept material are available at the GitHub PoC for CVE-2026-79298 and the GitHub UEFI Security Research repository.

Root Cause

The root cause is improper validation of attacker-controlled data parsed from cloak32.dat by the BOOTia32.efi bootloader. Data from the ESP is treated as trusted input during boot. This category aligns with Bootloader and BIOS/UEFI vulnerabilities that undermine platform trust anchors.

Attack Vector

Exploitation requires local access sufficient to write to the ESP, typically administrative privileges or physical access. The attacker places a crafted cloak32.dat file on the ESP alongside BOOTia32.efi. On the next boot, the vulnerable module processes the file and executes attacker-controlled code with UEFI privileges. Because the vulnerable binary may be signed and trusted, this can enable Secure Boot bypass and pre-OS persistence such as a bootkit.

No verified exploitation code is reproduced here. Refer to the linked research repositories for technical details.

Detection Methods for CVE-2026-79298

Indicators of Compromise

• Presence of cloak32.dat on the ESP on systems that do not run Howyar SysReturn
• Unexpected or modified BOOTia32.efi binaries in the ESP \EFI\ directory
• UEFI variable or boot order changes referencing SysReturn components outside of expected maintenance windows
• Secure Boot policy violations or dbx updates that fail to invalidate vulnerable Howyar binaries

Detection Strategies

• Inventory endpoints for installed SysReturn versions and flag any build below 11.3.0.34
• Hash and monitor UEFI files on the ESP, alerting on writes to BOOTia32.efi and cloak32.dat
• Correlate ESP modifications with process ancestry to identify the writing process and user context
• Ingest firmware and boot integrity telemetry into a data lake for retroactive hunting after new IOCs are published

Monitoring Recommendations

• Enable Measured Boot and validate TPM PCR values against a known-good baseline
• Alert on privileged file operations targeting \EFI\Boot\ and vendor-specific ESP paths
• Track UEFI variable modifications (BootOrder, Boot####) using platform telemetry
• Review Secure Boot revocation list (dbx) updates and confirm coverage of vulnerable Howyar hashes

How to Mitigate CVE-2026-79298

Immediate Actions Required

• Upgrade Howyar SysReturn to version 11.3.0.34 or later on all affected endpoints
• Restrict administrative and physical access that permits writes to the ESP
• Audit the ESP for unauthorized cloak32.dat files and remove them after forensic capture
• Verify Secure Boot is enabled and configured to enforce vendor signature policies

Patch Information

Howyar Technologies fixed the vulnerability in SysReturn v.11.3.0.34. Deploy the vendor-supplied update to replace the vulnerable BOOTia32.efi bootloader. After patching, confirm the new binary hash on the ESP and validate that Secure Boot revocation entries block the previous vulnerable version.

Workarounds

• Where patching is delayed, remove SysReturn UEFI components from the ESP on non-production hosts
• Enforce full-disk encryption to raise the cost of offline ESP tampering
• Apply UEFI firmware settings that require an administrator password for boot order and firmware changes
• Add vulnerable BOOTia32.efi hashes to the Secure Boot dbx where the platform supports custom revocation

# Example: verify SysReturn version and inspect ESP contents on Windows
mountvol X: /S
dir X:\EFI /S
certutil -hashfile X:\EFI\Boot\BOOTia32.efi SHA256
mountvol X: /D