Обход механизмов контроля привилегий
Adversaries may circumvent mechanisms designed to control elevate privileges to gain higher-level permissions. Most modern systems contain native elevation control mechanisms that are intended to limit privileges that a user can perform on a machine. Authorization has to be granted to specific users in order to perform tasks that can be considered of higher risk.(Citation: TechNet How UAC Works)(Citation: sudo man page 2018) An adversary can perform several methods to take advantage of built-in control mechanisms in order to escalate privileges on a system.(Citation: OSX Keydnap malware)(Citation: Fortinet Fareit)
Примеры процедур |
|
| Название | Описание |
|---|---|
| Raspberry Robin |
Raspberry Robin implements a variation of the |
Контрмеры |
|
| Контрмера | Описание |
|---|---|
| Execution Prevention |
Block execution of code on a system through application control, and/or script blocking. |
| Operating System Configuration |
Make configuration changes related to the operating system or a common feature of the operating system that result in system hardening against techniques. |
| Update Software |
Perform regular software updates to mitigate exploitation risk. |
| User Account Control |
Configure Windows User Account Control to mitigate risk of adversaries obtaining elevated process access. |
| Privileged Account Management |
Manage the creation, modification, use, and permissions associated to privileged accounts, including SYSTEM and root. |
| User Account Management |
Manage the creation, modification, use, and permissions associated to user accounts. |
| Audit |
Perform audits or scans of systems, permissions, insecure software, insecure configurations, etc. to identify potential weaknesses. |
| Restrict File and Directory Permissions |
Restrict access by setting directory and file permissions that are not specific to users or privileged accounts. |
Обнаружение
Monitor the file system for files that have the setuid or setgid bits set. Also look for any process API calls for behavior that may be indicative of Process Injection and unusual loaded DLLs through DLL Search Order Hijacking, which indicate attempts to gain access to higher privileged processes. On Linux, auditd can alert every time a user's actual ID and effective ID are different (this is what happens when you sudo).
Consider monitoring for /usr/libexec/security_authtrampoline executions which may indicate that AuthorizationExecuteWithPrivileges is being executed. MacOS system logs may also indicate when AuthorizationExecuteWithPrivileges is being called. Monitoring OS API callbacks for the execution can also be a way to detect this behavior but requires specialized security tooling.
On Linux, auditd can alert every time a user's actual ID and effective ID are different (this is what happens when you sudo). This technique is abusing normal functionality in macOS and Linux systems, but sudo has the ability to log all input and output based on the LOG_INPUT and LOG_OUTPUT directives in the /etc/sudoers file.
There are many ways to perform UAC bypasses when a user is in the local administrator group on a system, so it may be difficult to target detection on all variations. Efforts should likely be placed on mitigation and collecting enough information on process launches and actions that could be performed before and after a UAC bypass is performed. Some UAC bypass methods rely on modifying specific, user-accessible Registry settings. Analysts should monitor Registry settings for unauthorized changes.
Ссылки
- Todd C. Miller. (2018). Sudo Man Page. Retrieved March 19, 2018.
- Salvio, J., Joven, R. (2016, December 16). Malicious Macro Bypasses UAC to Elevate Privilege for Fareit Malware. Retrieved December 27, 2016.
- Marc-Etienne M.Leveille. (2016, July 6). New OSX/Keydnap malware is hungry for credentials. Retrieved July 3, 2017.
- Lich, B. (2016, May 31). How User Account Control Works. Retrieved June 3, 2016.
- UACME Project. (2016, June 16). UACMe. Retrieved July 26, 2016.
- Christopher So. (2022, December 20). Raspberry Robin Malware Targets Telecom, Governments. Retrieved May 17, 2024.
Связанные риски
Каталоги
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