RegPhantom Rootkit: Persistence Mechanisms and Mitigation
RegPhantom Watch: A Suspicious Hash With Agreement SHA-256 703dfb12…e7c4 draws consensus from two trusted reputation feeds and possible RegPhantom rootkit ties, but no behavioural detonation confirms intent.
- Malware
Bottom line. Treat the sample as suspicious, not benign. Apply detection (alert, do not block) and run a file-reputation and sandbox lookup to secure a strong, behavioural corroborator before promoting the verdict to malicious or closing it out.
Background
An automated IOC investigation flagged SHA-256 703dfb12edc6da592e3dfb951ca2d84bf349e6a16ad3a2ab32b275349956e7c4 as suspicious, with a risk score of 69/100 and possible ties to RegPhantom rootkit activity. The pipeline’s raw verdict of ‘likely malicious’ was deliberately downgraded to ‘suspicious’ because no strong, trusted-source-verified or high-confidence correlated signal was observed.
Two independent reputation feeds, VirusTotal and AlienVault OTX, agree on the sample, but source coverage was degraded: only two of eight configured providers returned usable data. The assessment is therefore reputation-led and provisional until behavioural evidence lands.
What we observed
Across the sources that did return data, three things stood out:
- VirusTotal consensus reported 37 malicious engine detections and 0 suspicious, strong reputation agreement, but reputation is not behaviour.
- AlienVault OTX independently corroborated the sample; the two feeds together flagged 21 of 29 co-submitted indicators, giving cross-source agreement rather than single-vendor noise.
- 21 of 29 submitted indicators share derived suspicious patterns, but these are heuristic/lexical rather than detonated behaviours, 0 strong, 42 moderate and 63 weak signals overall.
Attribution
The sample is loosely associated with RegPhantom rootkit activity on the basis of reputation labels only. No detonation, no host or infrastructure telemetry, and no campaign edges corroborate that link, so no actor or family is asserted with confidence. Reputation without behavioural confirmation can also reflect stale listings, scraper artefacts, or single-vendor false positives.
Confidence: 72%.
Two feeds agreeing is a reason to look harder, not a reason to stop looking.
Evidence signals by strength
Indicators of compromise
Defenders can block or hunt the following:
| Indicator | Type | Note |
|---|---|---|
| 703dfb12edc6da592e3dfb951ca2d84bf349e6a16ad3a2ab32b275349956e7c4 | sha256 | Primary sample, 37 VirusTotal malicious detections; corroborated by AlienVault OTX; possible RegPhantom rootkit ties |
Detection
Copy-ready hunting query:
DeviceFileEvents
| where SHA256 == "703dfb12edc6da592e3dfb951ca2d84bf349e6a16ad3a2ab32b275349956e7c4"
| project Timestamp, DeviceName, InitiatingProcessAccountName, FolderPath, FileName
| order by Timestamp descRecommendations
- Apply detection in alert-only mode (do not block yet) and queue a containment review pending one more corroborator.
- Run a file-reputation lookup and detonate the sample in a sandbox to obtain a strong, behavioural signal before promoting the verdict.
- Pull a second trusted source (secondary TI feed, passive DNS) and re-score; hunt endpoints for the exact SHA-256 to gauge prevalence.
