Modify Authentication Process T1556
Adversaries may modify authentication mechanisms and processes to access user credentials or enable otherwise unwarranted access to accounts. The authentication process is handled by mechanisms, such as the Local Security Authentication Server (LSASS) process and the Security Accounts Manager (SAM) on Windows, pluggable authentication modules (PAM) on Unix-based systems, and authorization plugins on MacOS systems, responsible for gathering, storing, and validating credentials. By modifying an authentication process, an adversary may be able to authenticate to a service or system without using Valid Accounts.
Events covered
17 catalog events are tagged with this technique by at least one rule.
Authoring guide
Patterns shared across the 14 rules above: which fields they filter on, what specific values they look for, and what they exclude. The catalog normalizes field names across vendors so Sigma's Image, Elastic's process.name, and Splunk's process_name collapse into one row. Each rule contributes at most once per row.
Fields filtered most (20 distinct)
The fields most rules look at when detecting this technique. The How column shows the operators authors use (eq, wildcard, regex_match, match) and how often each appears. Sample values are concrete examples to start from, not an exhaustive list.
Top indicator values (59 distinct)
Specific (field, operator, value) combinations the rules check for, ranked by how many rules under this technique use each one. The Corpus reach column counts how many rules across the entire catalog (any technique) check the same combination. High numbers point to widely-used indicators that are likely noisy on their own; combine them with another condition for useful signal. Blank means the combination is specific to rules under this technique. Click a value to expand the rules under this technique that use it.
Exclusions (15 distinct)
Field/operator/value combinations excluded by rules under this technique (top-level not() clauses), sorted by how many rules exclude each. These are the false-positive paths the community has learned to filter out. A new rule that ignores the high-count entries here will likely fire on the same noisy paths. Click a value to expand the rules under this technique that exclude it.
Rules under this technique
Every rule in the catalog tagged with this technique, grouped by vendor. Click a rule title for its full predicates, exclusions, and indicators.
Sigma 5 rules
- Directory Service Restore Mode(DSRM) Registry Value Tampering
- Dropping Of Password Filter DLL
- Possible Shadow Credentials Added
- Potential Suspicious Activity Using SeCEdit
- Powershell Install a DLL in System Directory
Elastic 3 rules
- Network Logon Provider Registry Modification
- Potential Shadow Credentials added to AD Object
- Untrusted DLL Loaded by Azure AD Connect Authentication Agent
Splunk 5 rules
- Disabling Windows Local Security Authority Defences via Registry
- Potential LSA password filter (PowerShell)
- Potential LSA password filter (Windows Event Log)
- Suspicious Certificate Authentication (Windows Event Log)
- Suspicious Certificate Modification (Windows Event Log)