tool

CORESHELL S0137

Type: malware
Platform: Windows
Created: 31 May 2017
Last modified: 22 October 2025

CORESHELL is a downloader used by APT28. The older versions of this malware are known as SOURFACE and newer versions as CORESHELL.[1] [2]

Techniques51st pct

Tactics41st pct

Threat groupunranked

CampaignsNone recorded

Enterprise ATT&CK only. Any Mobile or ICS rows on the same ATT&CK page are not carried.

MITRE reference S0137

Obfuscated Files or Information T1027↗

CORESHELL obfuscates strings using a custom stream cipher.3

Stealth116 detection rules

Junk Code Insertion T1027.016↗

CORESHELL contains unused machine instructions in a likely attempt to hinder analysis.4

Stealthno detection rules

Web Protocols T1071.001↗

CORESHELL can communicate over HTTP for C2.5 6

Command and Control57 detection rules

Mail Protocols T1071.003↗

CORESHELL can communicate over SMTP and POP3 for C2.7 8

Command and Control3 detection rules

System Information Discovery T1082↗

CORESHELL collects hostname and OS version data from the victim and sends the information to its C2 server.9

Discovery54 detection rules

Ingress Tool Transfer T1105↗

CORESHELL downloads another dropper from its C2 server.10

Command and Control129 detection rules

Standing S0137

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

Techniques1151st pct

51st percentile · 51% of 825 ATT&CK software entries have this many Enterprise techniques or fewer.

Tactics541st pct

41st percentile · 59% of 825 ATT&CK software entries have more tactics spanned.

Threat group161% 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 / technique46medTop 10%

90th percentile · 90% of 825 ATT&CK software entries have this many detection rules per technique or fewer.

Tests / technique3med

Detection coverage S0137

458 distinct rules cover the 11 techniques recorded for this tool. The 470 technique-to-rule mappings resolve to 458 distinct rules, because one rule can cover several techniques. 351 Sigma · 107 Splunk.

8 covered by at least one rule3 with no coverage458 distinct rules in total

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MITRE reference S0137

Reach

Coverage

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