# [HIGH] Qinglong task scheduler RCE vulnerabilities exploited in the wild for cryptomining

**Source:** Snyk
**Published:** 2026-04-27
**Article:** https://snyk.io/blog/qinglong-task-scheduler-rce-vulnerabilities/

## Threat Profile

Snyk Blog In this article
Written by Julia Kinday 
April 27, 2026
0 mins read In early February 2026, users of Qinglong (青龙), a popular open source timed task management platform with over 19,000 GitHub stars, began reporting that their servers were maxing out CPU usage. The cause was a cryptominer binary called .fullgc , deployed through two authentication bypass vulnerabilities that allowed unauthenticated remote code execution.
The attacks went largely unnoticed in the English-speaking securi…

## Indicators of Compromise (high-fidelity only)

- **CVE:** `CVE-2026-3965`
- **CVE:** `CVE-2026-4047`
- **Domain (defanged):** `file.551911.xyz`

## MITRE ATT&CK Techniques

- **T1190** — Exploit Public-Facing Application
- **T1053.005** — Scheduled Task
- **T1071** — Application Layer Protocol
- **T1204.002** — User Execution: Malicious File
- **T1556** — Modify Authentication Process
- **T1059.004** — Command and Scripting Interpreter: Unix Shell
- **T1071.001** — Application Layer Protocol: Web Protocols
- **T1105** — Ingress Tool Transfer
- **T1564.001** — Hide Artifacts: Hidden Files and Directories
- **T1036.005** — Masquerading: Match Legitimate Name or Location
- **T1496** — Resource Hijacking

## Kill chain phases observed

_(none detected from narrative keywords)_

## Recommended hunts

### Qinglong CVE-2026-3965 auth bypass via /open/user/init credential reset

`UC_353_4` · phase: **exploit** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats summariesonly=t count min(_time) as firstTime max(_time) as lastTime from datamodel=Web.Web where (Web.http_method="PUT" OR Web.http_method="POST") (Web.url="*/open/user/init*" OR Web.uri_path="*/open/user/init*") by Web.src, Web.dest, Web.url, Web.http_method, Web.http_user_agent, Web.status
| `drop_dm_object_name("Web")`
| eval qinglong_panel=if(match(dest_port,"5700") OR match(url,"5700"),"yes","unknown")
| where status>=200 AND status<400
| convert ctime(firstTime) ctime(lastTime)
```

**Defender KQL:**
```kql
// Defender XDR cannot observe inbound HTTP request paths to a Linux container app.
// Pivot to follow-on artefact: node (qinglong) process spawning a shell that touches
// the admin auth/config layer shortly after exploitation, OR the Qinglong app restarting
// unexpectedly (config.sh write triggers restart per article).
DeviceProcessEvents
| where Timestamp > ago(7d)
| where InitiatingProcessFileName in~ ("node","node.exe","pm2","ts-node")
| where InitiatingProcessCommandLine has_any ("qinglong","/ql/build","/ql/src","@whyour/qinglong")
| where FileName in~ ("sh","bash","dash","ash")
| where ProcessCommandLine has_any ("user/init","/open/user","config.sh","auth.db","db/auth")
| project Timestamp, DeviceName, AccountName, FileName, ProcessCommandLine, InitiatingProcessFileName, InitiatingProcessCommandLine, InitiatingProcessParentFileName
| order by Timestamp desc
```

### Qinglong CVE-2026-4047 case-mismatch auth bypass via /aPi/system/command-run

`UC_353_5` · phase: **exploit** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats summariesonly=t count min(_time) as firstTime max(_time) as lastTime from datamodel=Web.Web where (Web.url="*/aPi/*" OR Web.url="*/Api/*" OR Web.url="*/aPI/*" OR Web.url="*/APi/*" OR Web.url="*/ApI/*" OR Web.url="*/API/*" OR Web.uri_path="*/aPi/*" OR Web.uri_path="*/Api/*") (Web.url="*/system/command-run*" OR Web.url="*/system/run-script*" OR Web.url="*/crons*") by Web.src, Web.dest, Web.url, Web.http_method, Web.http_user_agent, Web.status
| `drop_dm_object_name("Web")`
| where status>=200 AND status<400
| convert ctime(firstTime) ctime(lastTime)
```

**Defender KQL:**
```kql
// Detects the qinglong node process spawning a shell with attacker-supplied command
// when CVE-2026-4047 is exploited against /aPi/system/command-run.
DeviceProcessEvents
| where Timestamp > ago(7d)
| where InitiatingProcessFileName in~ ("node","node.exe","pm2","ts-node")
| where InitiatingProcessCommandLine has_any ("qinglong","/ql/build","/ql/src","@whyour/qinglong")
| where FileName in~ ("sh","bash","dash","ash","curl","wget")
| where ProcessCommandLine has_any ("curl","wget","file.551911.xyz","/ql/data/db/.fullgc","nohup","chmod +x","$(uname","-fsSL")
  or ProcessCommandLine matches regex @"(?i)>\s*/dev/null\s+2>&1\s+&"
| project Timestamp, DeviceName, AccountName, FileName, ProcessCommandLine, InitiatingProcessFileName, InitiatingProcessCommandLine, InitiatingProcessParentFileName, SHA256
| order by Timestamp desc
```

### Qinglong cryptominer payload download from file.551911.xyz

`UC_353_6` · phase: **delivery** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats summariesonly=t count min(_time) as firstTime max(_time) as lastTime from datamodel=Network_Resolution.DNS where (DNS.query="file.551911.xyz" OR DNS.query="*.551911.xyz") by DNS.src, DNS.dest, DNS.query, DNS.answer
| `drop_dm_object_name("DNS")`
| append [
  | tstats summariesonly=t count from datamodel=Endpoint.Processes where (Processes.process_name="curl" OR Processes.process_name="wget") (Processes.process="*file.551911.xyz*" OR Processes.process="*fullgc/Linux*" OR Processes.process="*fullgc/Darwin*") by Processes.dest, Processes.user, Processes.process_name, Processes.process, Processes.parent_process_name
  | `drop_dm_object_name("Processes")`
]
| convert ctime(firstTime) ctime(lastTime)
```

**Defender KQL:**
```kql
// DNS / network egress + curl/wget command line referencing the article's exact payload host
let PayloadHost = dynamic(["file.551911.xyz",".551911.xyz"]);
let NetHits = DeviceNetworkEvents
| where Timestamp > ago(30d)
| where RemoteUrl has_any (PayloadHost) or RemoteUrl matches regex @"(?i)file\.551911\.xyz"
| project Timestamp, DeviceName, ActionType, RemoteUrl, RemoteIP, RemotePort, InitiatingProcessFileName, InitiatingProcessCommandLine, InitiatingProcessAccountName;
let ProcHits = DeviceProcessEvents
| where Timestamp > ago(30d)
| where FileName in~ ("curl","wget","fetch","aria2c")
| where ProcessCommandLine has_any ("file.551911.xyz","fullgc/Linux","fullgc/Darwin","fullgc/$(uname")
| project Timestamp, DeviceName, ActionType="ProcessCreated", RemoteUrl=tostring(parse_url(ProcessCommandLine).Host), RemoteIP="", RemotePort=int(null), InitiatingProcessFileName=FileName, InitiatingProcessCommandLine=ProcessCommandLine, InitiatingProcessAccountName=AccountName;
union NetHits, ProcHits
| order by Timestamp desc
```

### Hidden .fullgc cryptominer binary written to /ql/data/db/

`UC_353_7` · phase: **install** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats summariesonly=t count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Filesystem where (Filesystem.file_path="/ql/data/db/.fullgc" OR Filesystem.file_name=".fullgc") by Filesystem.dest, Filesystem.user, Filesystem.file_path, Filesystem.file_name, Filesystem.process_id, Filesystem.process_name, Filesystem.action
| `drop_dm_object_name("Filesystem")`
| convert ctime(firstTime) ctime(lastTime)
```

**Defender KQL:**
```kql
DeviceFileEvents
| where Timestamp > ago(30d)
| where ActionType in ("FileCreated","FileRenamed","FileModified")
| where (FolderPath has "/ql/data/db" and FileName == ".fullgc")
   or FolderPath endswith "/ql/data/db/.fullgc"
   or FileName == ".fullgc"
| project Timestamp, DeviceName, ActionType, FolderPath, FileName, SHA256, FileSize, InitiatingProcessFileName, InitiatingProcessCommandLine, InitiatingProcessAccountName, InitiatingProcessParentFileName
| order by Timestamp desc
```

### Qinglong .fullgc cryptominer execution with nohup backgrounding

`UC_353_8` · phase: **install** · confidence: **High** · AI-generated for this article

**Splunk SPL (CIM):**
```spl
| tstats summariesonly=t count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where (Processes.process_name=".fullgc" OR Processes.process="*/ql/data/db/.fullgc*" OR Processes.process="*.fullgc*nohup*" OR Processes.process="*nohup*.fullgc*") by Processes.dest, Processes.user, Processes.process_name, Processes.process, Processes.parent_process_name, Processes.parent_process
| `drop_dm_object_name("Processes")`
| eval suppressed_output=if(match(process,"(?i)>/dev/null\s+2>&1"),"yes","no")
| eval backgrounded=if(match(process,"&\s*$"),"yes","no")
| convert ctime(firstTime) ctime(lastTime)
```

**Defender KQL:**
```kql
DeviceProcessEvents
| where Timestamp > ago(30d)
| where (FileName == ".fullgc")
   or FolderPath endswith "/ql/data/db/.fullgc"
   or ProcessCommandLine has "/ql/data/db/.fullgc"
   or (InitiatingProcessFileName in~ ("sh","bash","dash","nohup") and ProcessCommandLine matches regex @"(?i)nohup\s+[\"']?[^\s]*\.fullgc")
| extend OutputSuppressed = tostring(ProcessCommandLine) matches regex @"(?i)>\s*/dev/null\s+2>&1"
| extend Backgrounded = tostring(ProcessCommandLine) matches regex @"&\s*$"
| project Timestamp, DeviceName, AccountName, FileName, FolderPath, ProcessCommandLine, SHA256, MD5, InitiatingProcessFileName, InitiatingProcessCommandLine, InitiatingProcessParentFileName, OutputSuppressed, Backgrounded
| order by Timestamp desc
```

### Scheduled task created with suspicious image / encoded args

`UC_SCHEDULED_TASK` · phase: **install** · confidence: **High**

**Splunk SPL (CIM):**
```spl
| tstats `summariesonly` count min(_time) as firstTime max(_time) as lastTime
    from datamodel=Endpoint.Processes
    where Processes.process_name="schtasks.exe" AND Processes.process="*/create*"
      AND (Processes.process="*powershell*" OR Processes.process="*cmd.exe*"
        OR Processes.process="*rundll32*" OR Processes.process="*-enc*"
        OR Processes.process="*FromBase64*" OR Processes.process="*\Users\Public*"
        OR Processes.process="*\AppData\*")
    by Processes.dest, Processes.user, Processes.process, Processes.parent_process_name
| `drop_dm_object_name(Processes)`
```

**Defender KQL:**
```kql
DeviceProcessEvents
| where Timestamp > ago(7d)
| where AccountName !endswith "$"
| where FileName =~ "schtasks.exe"
| where ProcessCommandLine has "/create"
| where ProcessCommandLine has_any ("powershell","cmd.exe","rundll32","-enc","FromBase64","\Users\Public","\AppData\")
| project Timestamp, DeviceName, AccountName, ProcessCommandLine, InitiatingProcessFileName
```

### Article-specific behavioural hunt — Qinglong task scheduler RCE vulnerabilities exploited in the wild for cryptomini

`UC_353_3` · phase: **exploit** · confidence: **High**

**Splunk SPL (CIM):**
```spl
``` Article-specific bespoke detection — Qinglong task scheduler RCE vulnerabilities exploited in the wild for cryptomini ```
| tstats `summariesonly` count earliest(_time) AS firstTime latest(_time) AS lastTime
    from datamodel=Endpoint.Processes
    where (Processes.process_name IN ("express.js","next.js","config.sh"))
    by Processes.dest, Processes.user, Processes.process_name,
       Processes.process, Processes.parent_process_name, Processes.process_path
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| append [
| tstats `summariesonly` count
    from datamodel=Endpoint.Filesystem
    where Filesystem.action IN ("created","modified")
      AND (Filesystem.file_path="*/dev/null*" OR Filesystem.file_name IN ("express.js","next.js","config.sh"))
    by Filesystem.dest, Filesystem.user, Filesystem.process_name,
       Filesystem.file_path, Filesystem.file_name
| `drop_dm_object_name(Filesystem)`
]
```

**Defender KQL:**
```kql
// Article-specific bespoke detection — Qinglong task scheduler RCE vulnerabilities exploited in the wild for cryptomini
// Hunts the actual binaries / paths / commandline fragments named
// in the article instead of a generic technique-class template.
DeviceProcessEvents
| where Timestamp > ago(30d)
| where (FileName in~ ("express.js", "next.js", "config.sh"))
| project Timestamp, DeviceName, AccountName, FileName,
          FolderPath, ProcessCommandLine,
          InitiatingProcessFileName, InitiatingProcessCommandLine
| order by Timestamp desc

// File-creation events for the named binaries / paths
DeviceFileEvents
| where Timestamp > ago(30d)
| where ActionType in ("FileCreated","FileModified")
| where (FolderPath has_any ("/dev/null") or FileName in~ ("express.js", "next.js", "config.sh"))
| project Timestamp, DeviceName, AccountName, FolderPath,
          FileName, ActionType, InitiatingProcessFileName,
          InitiatingProcessCommandLine
| order by Timestamp desc
```

### IOC-driven hunts (use shared templates)

These are standard IOC-substitution hunts — the canonical SPL and KQL live once in [`_TEMPLATES.md`](../_TEMPLATES.md), so we don't repeat the same boilerplate on every CVE / hash / network-IOC briefing.

- **Asset exposure — vulnerability matches article CVE(s)** ([template](../_TEMPLATES.md#asset-exposure)) — phase: **recon**, confidence: **High**
  - CVE(s): `CVE-2026-3965`, `CVE-2026-4047`

- **Network connections to article IPs / domains** ([template](../_TEMPLATES.md#network-ioc)) — phase: **c2**, confidence: **High**
  - IP / domain IOC(s): `file.551911.xyz`


## Why this matters

Severity classified as **HIGH** based on: CVE present, IOCs present, 9 use case(s) fired, 11 technique(s) inferred. Read the full article for actor attribution, tooling details, and any defanged IOCs in the body that aren't visible in the RSS summary.