Adversaries may search compromised systems to find and obtain insecurely stored credentials. These credentials can be stored and/or misplaced in many locations on a system, including plaintext files (e.g. Bash History), operating system or application-specific repositories (e.g. Credentials in Registry), or other specialized files/artifacts (e.g. Private Keys).
|Active Directory Configuration||
Remove vulnerable Group Policy Preferences.
Preemptively search for files containing passwords or other credentials and take actions to reduce the exposure risk when found.
|Encrypt Sensitive Information||
When possible, store keys on separate cryptographic hardware instead of on the local system.
|Filter Network Traffic||
Limit access to the Instance Metadata API using a host-based firewall such as iptables. A properly configured Web Application Firewall (WAF) may help prevent external adversaries from exploiting Server-side Request Forgery (SSRF) attacks that allow access to the Cloud Instance Metadata API.
|Operating System Configuration||
There are multiple methods of preventing a user's command history from being flushed to their .bash_history file, including use of the following commands:
Use strong passphrases for private keys to make cracking difficult. Do not store credentials within the Registry. Establish an organizational policy that prohibits password storage in files.
|Privileged Account Management||
If it is necessary that software must store credentials in the Registry, then ensure the associated accounts have limited permissions so they cannot be abused if obtained by an adversary.
|Restrict File and Directory Permissions||
Restrict file shares to specific directories with access only to necessary users.
Ensure that developers and system administrators are aware of the risk associated with having plaintext passwords in software configuration files that may be left on endpoint systems or servers.
While detecting adversaries accessing credentials may be difficult without knowing they exist in the environment, it may be possible to detect adversary use of credentials they have obtained. Monitor the command-line arguments of executing processes for suspicious words or regular expressions that may indicate searching for a password (for example: password, pwd, login, secure, or credentials). See Valid Accounts for more information.
Monitor for suspicious file access activity, specifically indications that a process is reading multiple files in a short amount of time and/or using command-line arguments indicative of searching for credential material (ex: regex patterns). These may be indicators of automated/scripted credential access behavior.
Monitoring when the user's
.bash_history is read can help alert to suspicious activity. While users do typically rely on their history of commands, they often access this history through other utilities like "history" instead of commands like
Additionally, monitor processes for applications that can be used to query the Registry, such as Reg, and collect command parameters that may indicate credentials are being searched. Correlate activity with related suspicious behavior that may indicate an active intrusion to reduce false positives.
- Microsoft. (2014, May 13). MS14-025: Vulnerability in Group Policy Preferences could allow elevation of privilege. Retrieved January 28, 2015.
- Higashi, Michael. (2018, May 15). Instance Metadata API: A Modern Day Trojan Horse. Retrieved July 16, 2019.
- Sean Metcalf. (2015, December 28). Finding Passwords in SYSVOL & Exploiting Group Policy Preferences. Retrieved February 17, 2020.