Detect Rclone RCD Unauthenticated Command Execution via Inline Remote Instantiation (CVE-2026-49980) in Google Chronicle
CVE-2026-49980 is a critical unauthenticated remote code execution vulnerability in Rclone versions 1.46.0 through 1.74.2. When the rclone remote control daemon (rcd) is started with the --rc-serve flag, an attacker can instantiate arbitrary remotes inline via the RC API without authentication, bypassing the fix introduced for CVE-2026-41179. This allows execution of arbitrary commands on the host running rclone rcd. CVSS 9.8. PoC is publicly available.
MITRE ATT&CK
YARA-L Detection Query
rule cve_2026_49980_rclone_rcd_unauthenticated_exec {
meta:
author = "df00tech Detection Engineering"
description = "Detects rclone rcd launched with --rc-serve and related RC API activity indicative of CVE-2026-49980"
severity = "CRITICAL"
yara_version = "YL2.0"
rule_version = "1.0"
events:
(
$e.metadata.event_type = "PROCESS_LAUNCH"
and re.regex($e.principal.process.file.full_path, `(?i)rclone(\.exe)?$`)
and (
re.regex($e.principal.process.command_line, `(?i)\brcd\b`)
or re.regex($e.principal.process.command_line, `(?i)--rc-serve`)
)
)
or
(
$e.metadata.event_type = "NETWORK_CONNECTION"
and $e.target.port = 5572
)
condition:
$e
}Chronicle YARA-L 2.0 rule detecting rclone rcd process launches with rc-serve flag and network connections targeting port 5572, mapping to CVE-2026-49980.
Data Sources
Required Tables
False Positives & Tuning
- Sanctioned use of rclone rcd in GCP environments with authentication and VPC controls
- Automated data pipeline tooling using rclone with RC API in restricted network segments
- Security research or threat hunting exercises against isolated hosts
Other platforms for CVE-2026-49980
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Unauthenticated rclone rcd RC API probe
Expected signal: Process creation event for rclone with arguments including rcd and --rc-no-auth; network bind event on port 5572; outbound HTTP POST to 127.0.0.1:5572
- Test 2Inline remote instantiation via unauthenticated RC API
Expected signal: HTTP POST to /config/create on port 5572; rclone process spawned with --rc-no-auth; possible rclone.conf modification event
- Test 3Remote command execution via rclone RC /core/command endpoint
Expected signal: HTTP POST to /core/command; rclone process with --rc-no-auth flag in process tree; network event on port 5572 from unexpected source
Unlock Pro Content
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