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Upgrade to ProDetect Chunked Multi-Paste Exfiltration to Text Storage Dead Drops in Google Chronicle
Free-tier text storage sites (Pastebin, dpaste, Ghostbin, paste.ee) enforce per-paste size caps that typically range from 512KB to a few megabytes. Adversaries and data-extortion crews exfiltrating a large staged archive (credential dumps, database exports, source code trees) via these services split the payload into sequential chunks — using `split`, PowerShell `Get-Content -ReadCount`, or a bundled exfil script — and upload each chunk as a separate paste, sometimes across multiple throwaway accounts to evade per-account rate limiting. This defeats naive single-event, single-large-transfer detection because no individual upload looks abnormal in isolation; the signal only emerges from correlating a burst of same-host, same-account paste-site uploads within a short window, each falling suspiciously below the platform's known size ceiling. This pattern is distinct from the ad-hoc single-paste developer or IR-analyst use already covered by the base T1567.003 technique detection: it requires both a local file-splitting or chunk-naming precursor and a subsequent burst of small, same-destination uploads. Both data-extortion crews staging data ahead of ransom negotiation and espionage actors moving smaller artifacts are known to use public paste and text-storage sites as dead drops; chunking credential material across many small pastes specifically evades proxy-level DLP thresholds tuned to single-request byte counts.
MITRE ATT&CK
- Tactic
- Exfiltration
YARA-L Detection Query
rule chunked_paste_dead_drop_exfiltration {
meta:
author = "df00tech"
description = "Detects bursts of small paste-site uploads from the same host/user, consistent with chunked exfiltration evading per-paste size caps"
severity = "HIGH"
mitre_attack_tactic = "Exfiltration"
mitre_attack_technique = "T1567.003"
threat_actors = "data-extortion and ransomware affiliates, espionage actors"
reference = "https://attack.mitre.org/techniques/T1567/003/"
events:
$e.metadata.event_type = "NETWORK_CONNECTION"
re.regex($e.target.hostname, `(?i)(pastebin\.com|hastebin\.com|ghostbin|paste\.ee|dpaste|sprunge\.us|ix\.io|termbin|controlc\.com|rentry\.co)`)
$hostname = $e.principal.hostname
$user = $e.principal.user.userid
match:
$hostname, $user over 15m
condition:
#e >= 3
}Chronicle YARA-L 2.0 rule using a 15-minute match window keyed on hostname and user, firing when three or more NETWORK_CONNECTION events to known paste-site domains occur from the same principal within the window — the burst-upload signal for chunked dead-drop exfiltration.
Data Sources
Required Tables
False Positives & Tuning
- CI/CD pipelines publishing multiple build logs as separate pastes within a short run
- Legitimate log-splitting scripts unrelated to paste-site exfiltration
Other platforms for THREAT-PasteSite-ChunkedDeadDropExfil
Testing Methodology
Validate this detection against 2 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 1Split a Staged File and Upload as Multiple Pastebin Chunks
Expected signal: Process creation event for `split` with `-b 100k` and an output prefix argument. Three or more curl process creation events within a short window, each with a command line referencing pastebin.com/api/api_post.php. Corresponding network connection events to pastebin.com on port 443 for each curl invocation.
- Test 2PowerShell Chunked Read-and-Upload Loop to dpaste
Expected signal: Sysmon Event ID 1 for powershell.exe with CommandLine containing 'Get-Content', 'ReadCount', and 'dpaste.org'. Multiple Sysmon Event ID 3 network connections from powershell.exe to dpaste.org within the same execution window. PowerShell ScriptBlock Log Event ID 4104 capturing the full loop.
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Related Detections
Tactic Hub
Detection Variants (1)
Different telemetry and tradecraft for the same technique — pick the one that matches the data you collect.