Umbreon hides from defenders by hooking libc function calls, hiding artifacts that would reveal its presence, such as the user account it creates to provide access and undermining strace, a tool often used to identify malware.1
tool
Umbreon S0221
- Type
- malware
- Platform
- Linux
- Created
- 18 April 2018
- Last modified
- 25 April 2025
A Linux rootkit that provides backdoor access and hides from defenders.
5
TechniquesBottom 23%
6
Tactics53rd pct
0
Threat groupsNone recorded
0
CampaignsNone recorded
Enterprise ATT&CK only. Any Mobile or ICS rows on the same ATT&CK page are not carried.
MITRE reference S0221
Umbreon provides access using both standard facilities like SSH and additional access using its backdoor Espeon, providing a reverse shell upon receipt of a special packet2
Umbreon creates valid local users to provide access to the system.3
Umbreon provides access to the system via SSH or any other protocol that uses PAM to authenticate.4
Umbreon provides additional access using its backdoor Espeon, providing a reverse shell upon receipt of a special packet.5
Standing S0221
Reach is how much of ATT&CK this tool touches. Coverage is how well defended each thing it does is, as a median per technique rather than a total — a total would just restate the reach. Each figure is ranked against all 825 ATT&CK software entries only where that population actually spreads. Where most of the population shares one value, a percentile would rank the tie instead of the entity, so the raw value is shown and no rank is claimed.
Reach
Techniques5Bottom 23%
23rd percentile · 77% of 825 ATT&CK software entries have more Enterprise techniques.
Tactics653rd pct
53rd percentile · 53% of 825 ATT&CK software entries have this many tactics spanned or fewer.
Threat groups061% tie · 22 values
61% of the population shares a single value across only 22 distinct values, so a percentile here would rank the tie, not the entity.
Campaigns085% tie · 8 values
85% of the population shares a single value across only 8 distinct values, so a percentile here would rank the tie, not the entity.
Coverage
Rules / technique6medBottom 8%
8th percentile · 92% of 825 ATT&CK software entries have more detection rules per technique.
Tests / technique4med
Detection coverage S0221
82 distinct rules cover the 5 techniques recorded for this tool. 55 Sigma · 27 Splunk.
4 covered by at least one rule1 with no coverage82 distinct rules in total
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