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In a WordPress compromise analyzed by Sucuri, malware called SC persisted in files, the database and shared memory, allowing surviving components to restore ones that had been removed. Its backdoor also used public Ethereum RPC gateways to fetch instructions. That explains why deleting visible files alone could fail; it does not mean Ethereum was compromised or that every infected site suffered payment theft.
What Sucuri found in the SC case
Sucuri security analyst Gabriel Barbosa described the incident on September 30, 2026, after encountering the backdoor during website cleanup and seeing it return seconds after removals. The label SC comes from “SC_” markers in injected content. In the examined infection, Sucuri found payload copies in at least eight locations. That is a finding about this case, not a measure of how common SC is or a fixed blueprint for every infection. Read Barbosa’s analysis.
| Where it persisted | Examples Sucuri described | Why it matters |
|---|---|---|
| Configuration and loader files | A .user.ini directive setting auto_prepend_file, plus loader or shim files |
The directive can make PHP load malicious code automatically during requests. |
| WordPress drop-ins and theme code | db.php, advanced-cache.php, and a marked block in the active theme’s functions.php |
These locations can execute as part of normal site or caching behavior. |
| Plugin directories | Matching fake-plugin payloads in mu-plugins and plugins |
Copies in separate locations can preserve an alternate route to execution. |
| Database and memory | An encoded payload in a database option and a System V shared-memory segment | These copies are not ordinary plugin or theme files, so a file-only cleanup can miss them. |
| Other persistence mechanisms in related variants | Scheduled tasks and database triggers | They can restore or run malicious code even after visible files are removed. |
File names can vary between sites. A suspicious file or code marker is an indicator to investigate, not by itself proof that every listed component is present.
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The analyzed payload included selectors and a list of roughly twenty public Ethereum RPC gateways that it could query for smart-contract instructions. RPC gateways are services for interacting with a blockchain; Sucuri’s finding was that the malware abused legitimate public infrastructure as a command channel. It was not evidence of an attack on the Ethereum network. Because the payload had multiple gateway choices, blocking one observed endpoint alone may leave alternatives available.
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What the backdoor could do
Sucuri reported that the payload fingerprinted the WordPress environment and collected details such as site versions, paths and administrator session tokens, then sent encrypted data. It could receive front-end JavaScript or PHP, deactivate and delete security plugins, and create or hide privileged administrator accounts.
On an online store, injected checkout JavaScript could capture payment information. The report describes that as a capability and risk, not a confirmed outcome for every site in the case. The impact depends on what code was delivered and where it ran.
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Signs worth investigating
Sucuri’s indicators are specific to its SC analysis, not a complete signature for all WordPress malware. Investigate unexpected findings such as:
- SC-style code in
wp-content/db.phporadvanced-cache.php. - A marked injected block in the active theme’s
functions.php, or an unexpectedauto_prepend_filedirective in.user.ini. - A fake or unfamiliar plugin duplicated between
mu-pluginsandplugins. - Randomly named ZIP archives that appear to be restore bundles.
- A large encoded blob in the WordPress options table or an unexpected PHP segment in shared memory.
- Hidden or otherwise suspicious administrator accounts.
- Outbound connections from the web server to public Ethereum RPC gateways.
Any one sign needs context. Compare files and settings with known-good backups, review account and server activity, and have a qualified incident responder or hosting provider help interpret findings if you cannot establish what is legitimate.
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Why malware can return after file cleanup
A file deletion removes only that copy. In this case, a surviving loader, database payload, memory segment, scheduled task or trigger could preserve another execution path or recreate a removed component. Sucuri’s description of the infection as a self-reinforcing mesh is useful here: cleanup has to account for the routes that execute and restore the payload, not just the most visible file.
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Sucuri’s order is important: stop the malicious code from executing safely, remove off-disk copies and persistence mechanisms, then remove the file-based components. This is specialist incident response, not a sufficient do-it-yourself checklist for an established compromise.
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- Contain and preserve access. Coordinate with the host or an incident responder, preserve evidence needed to understand the entry point, and prevent further exposure where possible. Avoid deleting files at random while the site may still be executing them.
- Neutralize the prepend target before changing the directive. Identify the file targeted by the
auto_prepend_filesetting and make it safe before stripping the directive. PHP can cache the prepend value; careless removal may break requests or leave the malicious target in use. - Remove off-disk payloads and control data. Check and clean the encoded database option and shared-memory segment, along with any related control data. On shared hosting, removing a System V shared-memory segment may require the host or its owner.
- Remove other persistence and access. Find and remove malicious scheduled tasks, audit database triggers, and remove hidden or unauthorized administrator accounts.
- Clean the file-based components. Remove loaders, fake-plugin copies, restore archives, malicious drop-ins and injected theme code. Verify the active theme and relevant configuration rather than assuming the first suspicious file was the only one.
- Rescan and monitor. Recheck the site and watch for recreated components. If they return, treat that as evidence that persistence or the original entry point remains; deleting the new copy again does not resolve the cause.
- Rotate credentials. After containment and cleanup, change WordPress administrator and other potentially exposed credentials, and review access for accounts that should not remain.
Reducing the chance of another compromise
For prevention, Barbosa recommends promptly patching WordPress and its components, using a web application firewall (WAF) to block exploit attempts and help stop beaconing, and regularly auditing database options, scheduled tasks, triggers and user accounts. These are recommendations in Sucuri’s incident report, not a guarantee against compromise or a comparative test of security products. Monitoring and prevention are not substitutes for removing an established persistence system.
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