Taint Shared Content
|Taint Shared Content|
|System Requirements||Access to shared folders and content with write permissions|
|Data Sources||File monitoring, Process monitoring|
Content stored on network drives or in other shared locations may be tainted by adding malicious programs, scripts, or exploit code to otherwise valid files. Once a user opens the shared tainted content, the malicious portion can be executed to run the adversary's code on a remote system. Adversaries may use tainted shared content to move laterally.
A directory share pivot is a variation on this technique that uses several other techniques to propagate malware when users access a shared network directory. It uses Shortcut Modification of directory .LNK files that use Masquerading to look like the real directories, which are hidden through Hidden Files and Directories. The malicious .LNK-based directories have an embedded command that executes the hidden malware file in the directory and then opens the real intended directory so that the user's expected action still occurs. When used with frequently used network directories, the technique may result in frequent reinfections and broad access to systems and potentially to new and higher privileged accounts.1
- Darkhotel uses a virus that propagates by infecting executables stored on shared drives.2
- H1N1 has functionality to copy itself to network shares.3
- Miner-C copies itself into the public folder of Network Attached Storage (NAS) devices and infects new victims who open the file.4
Protect shared folders by minimizing users who have write access. Use utilities that detect or mitigate common features used in exploitation, such as the Microsoft Enhanced Mitigation Experience Toolkit (EMET).
Reduce potential lateral movement risk by using web-based document management and collaboration services that do not use network file and directory sharing.
Identify potentially malicious software that may be used to taint content or may result from it and audit and/or block the unknown programs by using whitelisting5 tools, like AppLocker,67 or Software Restriction Policies8 where appropriate.9
Processes that write or overwrite many files to a network shared directory may be suspicious. Monitor processes that are executed from removable media for malicious or abnormal activity such as network connections due to Command and Control and possible network Discovery techniques.
Frequently scan shared network directories for malicious files, hidden files, .LNK files, and other file types that may not typical exist in directories used to share specific types of content.
- Routin, D. (2017, November 13). Abusing network shares for efficient lateral movements and privesc (DirSharePivot). Retrieved April 12, 2018.
- Kaspersky Lab's Global Research and Analysis Team. (2014, November). The Darkhotel APT A Story of Unusual Hospitality. Retrieved November 12, 2014.
- Reynolds, J.. (2016, September 14). H1N1: Technical analysis reveals new capabilities – part 2. Retrieved September 26, 2016.
- Cimpanu, C.. (2016, September 9). Cryptocurrency Mining Malware Discovered Targeting Seagate NAS Hard Drives. Retrieved October 12, 2016.
- Beechey, J. (2010, December). Application Whitelisting: Panacea or Propaganda?. Retrieved November 18, 2014.
- Tomonaga, S. (2016, January 26). Windows Commands Abused by Attackers. Retrieved February 2, 2016.
- NSA Information Assurance Directorate. (2014, August). Application Whitelisting Using Microsoft AppLocker. Retrieved March 31, 2016.
- Corio, C., & Sayana, D. P. (2008, June). Application Lockdown with Software Restriction Policies. Retrieved November 18, 2014.
- Microsoft. (2012, June 27). Using Software Restriction Policies and AppLocker Policies. Retrieved April 7, 2016.