Locky PDF malware analysis — malicious · 36fcbccf3bf8fb95

MALICIOUS

PDF

188.8 KB Authoring application: PyPDF2

MD5: 61c2236a51b5c30ccda2e088e9f6bf89 SHA-1: 0aab54a208f38b1dfa27f8dc3f10388773f4a197 SHA-256: 36fcbccf3bf8fb95ede1eba6339fac4559607c154fa26c262598c50e4d1a18b2

154 Risk Score

Malware Insights

Locky · confidence 95%

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

The file is a PDF containing embedded JavaScript, identified by multiple heuristics. ClamAV detections indicate the presence of the Locky ransomware family. The embedded JavaScript is likely responsible for downloading and executing a second-stage payload, as suggested by the 'PDF_JAVASCRIPT' and 'PDF_JS' heuristics and the 'Suspicious extracted artifact' signal. The presence of a URI pointing to an IRS document is a common lure for phishing attacks.

Heuristics 7

ClamAV: Win.Trojan.Locky-30621 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Win.Trojan.Locky-30621
ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV

ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
JavaScript action low PDF_JAVASCRIPT

PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
Embedded JS stream low PDF_JS

PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
String.fromCharCode low PDF_FROMCHARCODE

String.fromCharCode found — used to construct payload strings dynamically. Common in benign JavaScript libraries for codepoint manipulation, so this alone is informational; weaponised use is also caught by the dedicated fromCharCode-stage and exploit-shape rules.
External URI low PDF_URI

PDF contains an external URL action
Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE

One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0022_000.js` `9d53372837b406438429ce4c3ce1dbb2f436d230a1889da50754925d4a65f903`	pdf-javascript-stream	PDF /JS object 22 at offset 0x178C	24304 bytes
Detection ClamAV: Win.Trojan.Locky-30621 Obfuscation or payload: likely Carved artifact contains 3 eval/decoder/string-building token(s).
`javascript_obj0022_001.js` `ecaf92d2f39480127715dd92f822a4bf3b4b8177e551f597100dd83883ccb255`	pdf-javascript-stream	PDF /JS object 22 at offset 0x178C	53 bytes

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