| ID | Name |
|---|---|
| T1003.001 | LSASS Memory |
| T1003.002 | Security Account Manager |
| T1003.003 | NTDS |
| T1003.004 | LSA Secrets |
| T1003.005 | Cached Domain Credentials |
| T1003.006 | DCSync |
| T1003.007 | Proc Filesystem |
| T1003.008 | /etc/passwd and /etc/shadow |
Adversaries may attempt to dump the contents of /etc/passwd and /etc/shadow to enable offline password cracking. Most modern Linux operating systems use a combination of /etc/passwd and /etc/shadow to store user account information, including password hashes in /etc/shadow. By default, /etc/shadow is only readable by the root user.[1]
Linux stores user information such as user ID, group ID, home directory path, and login shell in /etc/passwd. A "user" on the system may belong to a person or a service. All password hashes are stored in /etc/shadow - including entries for users with no passwords and users with locked or disabled accounts.[1]
Adversaries may attempt to read or dump the /etc/passwd and /etc/shadow files on Linux systems via command line utilities such as the cat command.[2] Additionally, the Linux utility unshadow can be used to combine the two files in a format suited for password cracking utilities such as John the Ripper - for example, via the command /usr/bin/unshadow /etc/passwd /etc/shadow > /tmp/crack.password.db[3]. Since the user information stored in /etc/passwd are linked to the password hashes in /etc/shadow, an adversary would need to have access to both.
| ID | Name | Description |
|---|---|---|
| S0349 | LaZagne |
LaZagne can obtain credential information from /etc/shadow using the shadow.py module.[4] |
| C0045 | ShadowRay |
During ShadowRay, threat actors used |
| ID | Mitigation | Description |
|---|---|---|
| M1027 | Password Policies |
Ensure that root accounts have complex, unique passwords across all systems on the network. |
| M1026 | Privileged Account Management |
Follow best practices in restricting access to privileged accounts to avoid hostile programs from accessing such sensitive information. |
| ID | Name | Analytic ID | Analytic Description |
|---|---|---|---|
| DET0446 | Credential Access via /etc/passwd and /etc/shadow Parsing | AN1234 |
Adversaries attempt to read sensitive files such as /etc/passwd and /etc/shadow for credential dumping. This may involve access to the files directly via command-line utilities (e.g., cat, less), creation of backup copies, or parsing through post-exploitation frameworks. Multi-event correlation includes elevated process execution, file access/read on sensitive paths, and anomalous read behaviors tied to non-root or unusual users. |