Host data exfiltration via embedded pre-startup loader
Published Oct 8, 2025 · Updated Oct 8, 2025
Embedded malicious code in CCleaner 5.33.6162 and CCleaner Cloud 1.07.3191 allows attackers to exfiltrate Windows host data. A modified startup callback invokes a custom loader that decrypts an embedded blob, creates executable heap memory, and runs an in-memory payload that profiles the host and posts encoded telemetry to hard-coded or DGA-derived C2 infrastructure. Execution requires a 32-bit Windows installation and an active launch by an administrator; the payload can also run C2-supplied shellcode, while macOS and 64-bit builds are unaffected.
Summary
What happened
Embedded malicious code in CCleaner 5.33.6162 and CCleaner Cloud 1.07.3191 allows attackers to exfiltrate Windows host data. A modified startup callback invokes a custom loader that decrypts an embedded blob, creates executable heap memory, and runs an in-memory payload that profiles the host and posts encoded telemetry to hard-coded or DGA-derived C2 infrastructure. Execution requires a 32-bit Windows installation and an active launch by an administrator; the payload can also run C2-supplied shellcode, while macOS and 64-bit builds are unaffected.
The record
- CVE
- CVE-2017-20201
- Published
- Oct 8, 2025
- Updated
- Oct 8, 2025
- Vendor
- Gen Digital
- Product
- CCleaner
- Classifications
- CWE-506, T1195.002, T1620, T1041
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Oct 8, 2025CVE publishedPublication date reported by the CVE source.
- Oct 8, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=5.33.6162
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Reported exploitation
- Targeted second-stage payload deliveryexploit chain
- VulnCheck KEV listingknown exploited catalog
- Observed CCleaner backdoor infectionsreported exploitation
Technologies
Your stack
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Your stack
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