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ATT&CK Technique

SIP and Trust Provider Hijacking

T1553.003 · defense-impairment

Adversaries may tamper with SIP and trust provider components to mislead the operating system and application control tools when conducting signature validation checks. In user mode, Windows Authenticode digital signatures are used to verify a file's origin and integrity, variables that may be used to establish trust in signed code (ex: a driver with a valid Microsoft signature may be handled as safe). The signature validation process is handled via the WinVerifyTrust application programming interface (API) function, which accepts an inquiry and coordinates with the appropriate trust provider, which is responsible for validating parameters of a signature.

Because of the varying executable file types and corresponding signature formats, Microsoft created software components called Subject Interface Packages (SIPs) to provide a layer of abstraction between API functions and files. SIPs are responsible for enabling API functions to create, retrieve, calculate, and verify signatures. Unique SIPs exist for most file formats (Executable, PowerShell, Installer, etc., with catalog signing providing a catch-all) and are identified by globally unique identifiers (GUIDs).

Similar to Code Signing, adversaries may abuse this architecture to subvert trust controls and bypass security policies that allow only legitimately signed code to execute on a system. Adversaries may hijack SIP and trust provider components to mislead operating system and application control tools to classify malicious (or any) code as signed by: Modifying the Dll and FuncName Registry values in HKLM\SOFTWARE[\WOW6432Node\]Microsoft\Cryptography\OID\EncodingType 0\CryptSIPDllGetSignedDataMsg\{SIP_GUID} that point to the dynamic link library (DLL) providing a SIP’s CryptSIPDllGetSignedDataMsg function, which retrieves an encoded digital certificate from a signed file. By pointing to a maliciously-crafted DLL with an exported function that always returns a known good signature value (ex: a Microsoft signature for Portable Executables) rather than the file’s real signature, an adversary can apply an acceptable signature value to all files using that SIP (although a hash mismatch will likely occur, invalidating the signature, since the hash returned by the function will not match the value computed from the file). Modifying the Dll and FuncName Registry values in HKLM\SOFTWARE\[WOW6432Node\]Microsoft\Cryptography\OID\EncodingType 0\CryptSIPDllVerifyIndirectData\{SIP_GUID} that point to the DLL providing a SIP’s CryptSIPDllVerifyIndirectData function, which validates a file’s computed hash against the signed hash value.

By pointing to a maliciously-crafted DLL with an exported function that always returns TRUE (indicating that the validation was successful), an adversary can successfully validate any file (with a legitimate signature) using that SIP (with or without hijacking the previously mentioned CryptSIPDllGetSignedDataMsg function). This Registry value could also be redirected to a suitable exported function from an already present DLL, avoiding the requirement to drop and execute a new file on disk. Modifying the DLL and Function Registry values in HKLM\SOFTWARE\[WOW6432Node\]Microsoft\Cryptography\Providers\Trust\FinalPolicy\{trust provider GUID} that point to the DLL providing a trust provider’s FinalPolicy function, which is where the decoded and parsed signature is checked and the majority of trust decisions are made. Similar to hijacking SIP’s CryptSIPDllVerifyIndirectData function, this value can be redirected to a suitable exported function from an already present DLL or a maliciously-crafted DLL (though the implementation of a trust provider is complex). Note: The above hijacks are also possible without modifying the Registry via DLL search order hijacking.

Hijacking SIP or trust provider components can also enable persistent code execution, since these malicious components may be invoked by any application that performs code signing or signature validation.

Windows
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Actors Using This

2
commercial_cybercrime_uefi_bootkitBlackLotus
us_israel_joint_offensive_cyber_speculationFlame
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Atomic Tests

1
Executable Atomic Red Team test cases for exercising this technique in a lab. Copy a command, run it on the listed platform, confirm your detections fire.
command_promptelevatedwindowsSIP (Subject Interface Package) Hijacking via Custom DLL
Registers a DLL that logs signature checks, mimicking SIP hijacking. This test uses a DLL from https://github.com/gtworek/PSBits/tree/master/SIP and registers it using regsvr32, thereby causing the system to utilize it during signature checks, and logging said checks. 
regsvr32.exe #{dll_payload}
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Mitigations

3
MITRE ATT&CK mitigations - vendor-agnostic guidance for reducing exposure to this technique.
M1022Restrict File and Directory Permissions

Restricting file and directory permissions involves setting access controls at the file system level to limit which users, groups, or processes can read, write, or execute files. By configuring permissions appropriately, organizations can reduce the attack surface for adversaries seeking to access sensitive data, plant malicious code, or tamper with system files.

Enforce Least Privilege Permissions
  • Remove unnecessary write permissions on sensitive files and directories.
  • Use file ownership and groups to control access for specific roles. Example (Windows): Right-click the shared folder.
  • Properties.
  • Security tab.
  • Adjust permissions for NTFS ACLs.
Harden File Shares
  • Disable anonymous access to shared folders.
  • Enforce NTFS permissions for shared folders on Windows. Example: Set permissions to restrict write access to critical files, such as system executables (e.g., /bin or /sbin on Linux). Use tools like chown and chmod to assign file ownership and limit access. On Linux, apply: chmod 750 /etc/sensitive.conf `chown root:admin /etc/sensitive.
conf` File Integrity Monitoring (FIM)
  • Use tools like Tripwire, Wazuh, or OSSEC to monitor changes to critical file permissions.
Audit File System Access
  • Enable auditing to track permission changes or unauthorized access attempts.
  • Use auditd (Linux) or Event Viewer (Windows) to log activities.
Restrict Startup Directories
  • Configure permissions to prevent unauthorized writes to directories like C:\ProgramData\Microsoft\Windows\Start Menu. Example: Restrict write access to critical directories like /etc/, /usr/local/, and Windows directories such as C:\Windows\System32.
  • On Windows, use icacls to modify permissions: icacls "C:\Windows\System32" /inheritance:r /grant:r SYSTEM:(OI)(CI)F.
  • On Linux, monitor permissions using tools like lsattr or auditd.
M1024Restrict Registry Permissions

Restricting registry permissions involves configuring access control settings for sensitive registry keys and hives to ensure that only authorized users or processes can make modifications. By limiting access, organizations can prevent unauthorized changes that adversaries might use for persistence, privilege escalation, or defense evasion.

Review and Adjust Permissions on Critical Keys
  • Regularly review permissions on keys such as Run, RunOnce, and Services to ensure only authorized users have write access.
  • Use tools like icacls or PowerShell to automate permission adjustments. Enable Registry Auditing.
  • Enable auditing on sensitive keys to log access attempts.
  • Use Event Viewer or SIEM solutions to analyze logs and detect suspicious activity.
  • Example Audit Policy: auditpol /set /subcategory:"Registry" /success:enable /failure:enable Protect Credential-Related Hives.
  • Limit access to hives like SAM,SECURITY, and SYSTEM to prevent credential dumping or other unauthorized access.
  • Use LSA Protection to add an additional security layer for credential storage. Restrict Registry Editor Usage.
  • Use Group Policy to restrict access to regedit.exe for non-administrative users.
  • Block execution of registry editing tools on endpoints where they are unnecessary. Deploy Baseline Configuration Tools.
  • Use tools like Microsoft Security Compliance Toolkit or CIS Benchmarks to apply and maintain secure registry configurations.
Tools for Implementation Registry Permission Tools
  • Registry Editor (regedit): Built-in tool to manage registry permissions.
  • PowerShell: Automate permissions and manage keys. Set-ItemProperty -Path "HKLM:\Software\Microsoft\Windows\CurrentVersion\Run" -Name "KeyName" -Value "Value".
  • icacls: Command-line tool to modify ACLs.
Monitoring Tools
  • Sysmon: Monitor and log registry events.
  • Event Viewer: View registry access logs.
Policy Management Tools
  • Group Policy Management Console (GPMC): Enforce registry permissions via GPOs.
  • Microsoft Endpoint Manager: Deploy configuration baselines for registry permissions.
M1038Execution Prevention

Prevent the execution of unauthorized or malicious code on systems by implementing application control, script blocking, and other execution prevention mechanisms. This ensures that only trusted and authorized code is executed, reducing the risk of malware and unauthorized actions.

Application Control
  • Use Case: Use tools like AppLocker or Windows Defender Application Control (WDAC) to create whitelists of authorized applications and block unauthorized ones. On Linux, use tools like SELinux or AppArmor to define mandatory access control policies for application execution.
  • Implementation: Allow only digitally signed or pre-approved applications to execute on servers and endpoints. (e.g., `New-AppLockerPolicy -PolicyType Enforced -FilePath "C:\Policies\AppLocker.
xml"`) Script Blocking
  • Use Case: Use script control mechanisms to block unauthorized execution of scripts, such as PowerShell or JavaScript. Web Browsers: Use browser extensions or settings to block JavaScript execution from untrusted sources.
  • Implementation: Configure PowerShell to enforce Constrained Language Mode for non-administrator users. (e.g.
, Set-ExecutionPolicy AllSigned) Executable Blocking
  • Use Case: Prevent execution of binaries from suspicious locations, such as %TEMP% or %APPDATA% directories.
  • Implementation: Block execution of .exe, .bat, or .ps1 files from user-writable directories.
Dynamic Analysis Prevention
  • Use Case: Use behavior-based execution prevention tools to identify and block malicious activity in real time.
  • Implemenation: Employ EDR solutions that analyze runtime behavior and block suspicious code execution.
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Detection Coverage

1/6 layers
Coverage across standard detection surfaces. Rows marked none have no rule of that type mapped. Some are real blind spots worth closing; others are simply not applicable to this technique (e.g. YARA matches malware files, not network behaviour).
Behavioral / log (Sigma) 1
Analytics (MITRE CAR) none
Runtime / container (Falco) none
File / malware (YARA) none
Network (Suricata/Snort) none
Vuln scan (Nuclei) none
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