Subvert Trust Controls: Mark-of-the-Web (MOTW)
Other sub-techniques of Subvert Trust Controls (6)
Adversaries may abuse specific file formats to subvert Mark-of-the-Web (MOTW) controls. In Windows, when files are downloaded from the Internet, they are tagged with a hidden NTFS Alternate Data Stream (ADS) named Zone.Identifier with a specific value known as the MOTW.(Citation: Microsoft Zone.Identifier 2020) Files that are tagged with MOTW are protected and cannot perform certain actions. For example, starting in MS Office 10, if a MS Office file has the MOTW, it will open in Protected View. Executables tagged with the MOTW will be processed by Windows Defender SmartScreen that compares files with an allowlist of well-known executables. If the file in not known/trusted, SmartScreen will prevent the execution and warn the user not to run it.(Citation: Beek Use of VHD Dec 2020)(Citation: Outflank MotW 2020)(Citation: Intezer Russian APT Dec 2020)
Adversaries may abuse container files such as compressed/archive (.arj, .gzip) and/or disk image (.iso, .vhd) file formats to deliver malicious payloads that may not be tagged with MOTW. Container files downloaded from the Internet will be marked with MOTW but the files within may not inherit the MOTW after the container files are extracted and/or mounted. MOTW is a NTFS feature and many container files do not support NTFS alternative data streams. After a container file is extracted and/or mounted, the files contained within them may be treated as local files on disk and run without protections.(Citation: Beek Use of VHD Dec 2020)(Citation: Outflank MotW 2020)
Примеры процедур |
|
| Название | Описание |
|---|---|
| TA505 |
TA505 has used .iso files to deploy malicious .lnk files.(Citation: TrendMicro TA505 Aug 2019) |
| Amadey |
Amadey has modified the `:Zone.Identifier` in the ADS area to zero.(Citation: Korean FSI TA505 2020) |
| APT29 |
APT29 has embedded ISO images and VHDX files in HTML to evade Mark-of-the-Web.(Citation: ESET T3 Threat Report 2021) |
Контрмеры |
|
| Контрмера | Описание |
|---|---|
| Disable or Remove Feature or Program |
Remove or deny access to unnecessary and potentially vulnerable software to prevent abuse by adversaries. |
| Execution Prevention |
Block execution of code on a system through application control, and/or script blocking. |
Обнаружение
Monitor compressed/archive and image files downloaded from the Internet as the contents may not be tagged with the MOTW. Data and events should not be viewed in isolation, but as part of a chain of behavior that could lead to other activities.(Citation: Disable automount for ISO)
Ссылки
- wordmann. (2022, February 8). Disable Disc Imgage. Retrieved February 8, 2022.
- Microsoft. (2020, August 31). Zone.Identifier Stream Name. Retrieved February 22, 2021.
- Kennedy, J. (2020, December 9). A Zebra in Gopher's Clothing: Russian APT Uses COVID-19 Lures to Deliver Zebrocy. Retrieved February 22, 2021.
- Hegt, S. (2020, March 30). Mark-of-the-Web from a red team’s perspective. Retrieved February 22, 2021.
- Beek, C. (2020, December 3). Investigating the Use of VHD Files By Cybercriminals. Retrieved February 22, 2021.
- Dormann, W. (2019, September 4). The Dangers of VHD and VHDX Files. Retrieved March 16, 2021.
- Financial Security Institute. (2020, February 28). Profiling of TA505 Threat Group That Continues to Attack the Financial Sector. Retrieved July 14, 2022.
- Trend Micro. (2019, August 27). TA505: Variety in Use of ServHelper and FlawedAmmyy. Retrieved February 22, 2021.
- wdormann. (2019, August 29). Disable Windows Explorer file associations for Disc Image Mount. Retrieved April 16, 2022.
- ESET. (2022, February). THREAT REPORT T3 2021. Retrieved February 10, 2022.
Связанные риски
Каталоги
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