OS Credential Dumping: /etc/passwd and /etc/shadow T1003.008

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.

Events covered

2 catalog events are tagged with this technique by at least one rule.

Authoring guide

Patterns shared across the 1 rule 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 (7 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.

FieldRulesHowSample values
Image1eq 1, wildcard 1?:\users\*\appdata\local\packages\*\rootfs\usr\bin\bash, ?:\windows\system32\bash.exe
OriginalFileName1eq 1bash.exe
ParentCommandLine1starts_with 1bash
event.type1eq 1start
parent_process_name1eq 1wsl.exe
process.args1wildcard 1--exec, --system, -e
process_name1eq 1wsl.exe

Top indicator values (17 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.

FieldKindValueRules (here)Corpus reach
Imageeq
?:\windows\system32\bash.exe
1
Imagewildcard
?:\users\*\appdata\local\packages\*\rootfs\usr\bin\bash
1
OriginalFileNameeq
bash.exe
14
ParentCommandLinestarts_with
bash
1
event.typeeq
start
1241
parent_process_nameeq
wsl.exe
12
process.argswildcard
--exec
1
process.argswildcard
--system
1
process.argswildcard
-e
12
process.argswildcard
/etc/passwd
1
process.argswildcard
/etc/shadow
1
process.argswildcard
/mnt/c/*
1
process.argswildcard
bash
1
process.argswildcard
cat
1
process.argswildcard
curl
1
process.argswildcard
root
1
process_nameeq
wsl.exe
13

Exclusions (2 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.

FieldKindValueRules excluding
ParentImagewildcard
?:\program files (x86)\docker\*.exe
1
ParentImagewildcard
?:\program files\docker\*.exe
1

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.

Elastic 1 rule