Formbook PDF malware analysis — malicious · 180888bfe38fb784

MALICIOUS

PDF

196.0 KB First seen: 2022-02-24

MD5: 60fcb97dd9e3c0ce787db9885350d049 SHA-1: a115181ea8b31caf5187a3837847e07c334219f5 SHA-256: 180888bfe38fb7843583c469b893806ff0f9bb169c5e7be900779764742be229

238 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK

T1059.007 JavaScript T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The PDF contains embedded JavaScript that is flagged as a dropper, specifically using exportDataObject and nLaunch functions to initiate the execution of an embedded file. ClamAV detections confirm this is a downloader for the Formbook family. The ML classifier also strongly indicates maliciousness. The embedded file and the decompressed stream are therefore considered high-priority IOCs.

Machine Learning

Nyx PDF Classifier malicious score 0.9736

Heuristics 8

exportDataObject + nLaunch — embedded-file launch-on-open dropper critical PDF_JS_EXPORT_LAUNCH_DROPPER

PDF JavaScript calls exportDataObject() with nLaunch set, which extracts the document's embedded file and launches it in its default application. This is a launch-on-open dropper: the embedded file is the payload. No benign workflow auto-launches an extracted PDF attachment. (matched in decompressed stream)
ClamAV: Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0
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.
Embedded file low PDF_EMBEDDED

PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload
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. (matched inside decoded stream)
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. (matched inside decoded stream)
PDF paints image(s) but contains no text operators info PDF_IMAGE_ONLY_LURE

PDF has 2 image XObject(s) and the content stream contains no text-emitting operators (BT/ET, Tj, TJ, ', ") in either raw bytes or decompressed streams — this is the screenshot-as-PDF pattern used to bypass text-based scanners and to deliver instructions purely through rendered pixels. It is informational unless paired with invisible links or risky URI context.
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
`embedded_file_obj0022.bin` `ab6472f6a74e9e6cf73febe0c8044b90178e5c1db29be3b424e7089b25ecc626`	pdf-embedded-file	PDF EmbeddedFile object 22 at offset 0x3B0F	191096 bytes
Detection ClamAV: Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0 Obfuscation or payload: likely Carved artifact entropy is 7.96, consistent with packed or encrypted content.
`stream_006_off00030c99.bin` `c1ded0611c88bf8d6d193d5f605863581a82d4a4ae28b5ab0fb650d3bb0ca952`	decompressed-pdf-stream	PDF FlateDecoded stream at offset 0x30C99	929 bytes

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