BOOKWORM has modified HTTP POST requests to resemble legitimate communications.4
tool
BOOKWORM S1226
- Type
- malware
- Platform
- Windows
- Created
- 21 July 2025
- Last modified
- 21 October 2025
BOOKWORM is a modular trojan known to be leveraged by Mustang Panda and was first observed utilized in 2015. BOOKWORM was later updated in late 2021 and the fall of 2022 to launch shellcode represented as UUID parameters. [1][2][3]
17
Techniques72nd pct
9
TacticsTop 11%
1
Threat groupunranked
0
CampaignsNone recorded
Enterprise ATT&CK only. Any Mobile or ICS rows on the same ATT&CK page are not carried.
MITRE reference S1226
BOOKWORM has been delivered using self-extracting RAR archives.5
BOOKWORM has utilized Base64 encoding to obfuscate its payload.6
BOOKWORM has created services that attempt to resemble legitimate services to include a service named Microsoft Windows DeviceSync Service.8
BOOKWORM has used its KBLogger.dll module to capture keystrokes and stored them in a folder. 9
Standing S1226
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
Techniques1772nd pct
72nd percentile · 72% of 825 ATT&CK software entries have this many Enterprise techniques or fewer.
Tactics9Top 11%
89th percentile · 89% of 825 ATT&CK software entries have this many tactics spanned or fewer.
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 / technique12medBottom 21%
21st percentile · 79% of 825 ATT&CK software entries have more detection rules per technique.
Tests / technique5med
Detection coverage S1226
640 distinct rules cover the 17 techniques recorded for this tool. The 654 technique-to-rule mappings resolve to 640 distinct rules, because one rule can cover several techniques. 468 Sigma · 172 Splunk.
16 covered by at least one rule1 with no coverage640 distinct rules in total
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