File and Directory Permissions Modification: Изменение разрешений для файлов и каталогов (Windows)
Other sub-techniques of File and Directory Permissions Modification (2)
Adversaries may modify file or directory permissions/attributes to evade access control lists (ACLs) and access protected files.(Citation: Hybrid Analysis Icacls1 June 2018)(Citation: Hybrid Analysis Icacls2 May 2018) File and directory permissions are commonly managed by ACLs configured by the file or directory owner, or users with the appropriate permissions. File and directory ACL implementations vary by platform, but generally explicitly designate which users or groups can perform which actions (read, write, execute, etc.). Windows implements file and directory ACLs as Discretionary Access Control Lists (DACLs).(Citation: Microsoft DACL May 2018) Similar to a standard ACL, DACLs identifies the accounts that are allowed or denied access to a securable object. When an attempt is made to access a securable object, the system checks the access control entries in the DACL in order. If a matching entry is found, access to the object is granted. Otherwise, access is denied.(Citation: Microsoft Access Control Lists May 2018) Adversaries can interact with the DACLs using built-in Windows commands, such as `icacls`, `cacls`, `takeown`, and `attrib`, which can grant adversaries higher permissions on specific files and folders. Further, PowerShell provides cmdlets that can be used to retrieve or modify file and directory DACLs. Specific file and directory modifications may be a required step for many techniques, such as establishing Persistence via Accessibility Features, Boot or Logon Initialization Scripts, or tainting/hijacking other instrumental binary/configuration files via Hijack Execution Flow.
Примеры процедур |
|
| Название | Описание |
|---|---|
| JPIN |
JPIN can use the command-line utility cacls.exe to change file permissions.(Citation: Microsoft PLATINUM April 2016) |
| BitPaymer |
BitPaymer can use |
| Grandoreiro |
Grandoreiro can modify the binary ACL to prevent security tools from running.(Citation: ESET Grandoreiro April 2020) |
| Wizard Spider |
Wizard Spider has used the icacls command to modify access control to backup servers, providing them with full control of all the system folders.(Citation: Sophos New Ryuk Attack October 2020) |
| CaddyWiper |
CaddyWiper can modify ACL entries to take ownership of files.(Citation: Cisco CaddyWiper March 2022) |
| Ryuk |
Ryuk can launch |
| BlackCat |
BlackCat can use Windows commands such as `fsutil behavior set SymLinkEvaluation R2L:1` to redirect file system access to a different location after gaining access into compromised networks.(Citation: Microsoft BlackCat Jun 2022) |
| WannaCry |
WannaCry uses |
| WastedLocker |
WastedLocker has a command to take ownership of a file and reset the ACL permissions using the |
Контрмеры |
|
| Контрмера | Описание |
|---|---|
| Privileged Account Management |
Manage the creation, modification, use, and permissions associated to privileged accounts, including SYSTEM and root. |
| Restrict File and Directory Permissions |
Restrict access by setting directory and file permissions that are not specific to users or privileged accounts. |
Обнаружение
Monitor and investigate attempts to modify DACLs and file/directory ownership. Many of the commands used to modify DACLs and file/directory ownership are built-in system utilities and may generate a high false positive alert rate, so compare against baseline knowledge for how systems are typically used and correlate modification events with other indications of malicious activity where possible. Consider enabling file/directory permission change auditing on folders containing key binary/configuration files. For example, Windows Security Log events (Event ID 4670) are created when DACLs are modified.(Citation: EventTracker File Permissions Feb 2014)
Ссылки
- Netsurion. (2014, February 19). Monitoring File Permission Changes with the Windows Security Log. Retrieved August 19, 2018.
- Microsoft. (2018, May 30). DACLs and ACEs. Retrieved August 19, 2018.
- M. Satran, M. Jacobs. (2018, May 30). Access Control Lists. Retrieved February 4, 2020.
- Hybrid Analysis. (2018, May 30). 2a8efbfadd798f6111340f7c1c956bee.dll. Retrieved August 19, 2018.
- Hybrid Analysis. (2018, June 12). c9b65b764985dfd7a11d3faf599c56b8.exe. Retrieved August 19, 2018.
- Windows Defender Advanced Threat Hunting Team. (2016, April 29). PLATINUM: Targeted attacks in South and Southeast Asia. Retrieved February 15, 2018.
- Frankoff, S., Hartley, B. (2018, November 14). Big Game Hunting: The Evolution of INDRIK SPIDER From Dridex Wire Fraud to BitPaymer Targeted Ransomware. Retrieved January 6, 2021.
- ESET. (2020, April 28). Grandoreiro: How engorged can an EXE get?. Retrieved November 13, 2020.
- Sean Gallagher, Peter Mackenzie, Elida Leite, Syed Shahram, Bill Kearney, Anand Aijan, Sivagnanam Gn, Suraj Mundalik. (2020, October 14). They’re back: inside a new Ryuk ransomware attack. Retrieved October 14, 2020.
- Malhotra, A. (2022, March 15). Threat Advisory: CaddyWiper. Retrieved March 23, 2022.
- ANSSI. (2021, February 25). RYUK RANSOMWARE. Retrieved March 29, 2021.
- Microsoft Defender Threat Intelligence. (2022, June 13). The many lives of BlackCat ransomware. Retrieved December 20, 2022.
- Noerenberg, E., Costis, A., and Quist, N. (2017, May 16). A Technical Analysis of WannaCry Ransomware. Retrieved March 25, 2019.
- Antenucci, S., Pantazopoulos, N., Sandee, M. (2020, June 23). WastedLocker: A New Ransomware Variant Developed By The Evil Corp Group. Retrieved September 14, 2021.
Связанные риски
Каталоги
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