PDF malware analysis — malicious · 10cb76b5779351b6

MALICIOUS

PDF

244.6 KB

MD5: df3085c728295405ae0c225041980f94 SHA-1: 66f6da87eca6c8c5990bbbffb85dd155a4f082a8 SHA-256: 10cb76b5779351b69610edbc34d4d3066cd55c9d3ab1722826bf545a9e654902

390 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

This PDF file contains a critical PDF_LAUNCH heuristic firing, indicating it attempts to execute cmd.exe. Further analysis reveals that cmd.exe is used to decode and execute a PE payload, identified by the PDF_VBS_DECIMAL_ARRAY_PE_PAYLOAD heuristic. This payload has a SHA256 hash of fc780efe356258258a01f4ef29e7842b82bd048555a8137a70fe030de04ff0ac and was extracted as decimal_array_pdf_pe_00000229.exe. The embedded script also contains a decimal array that decodes to this PE payload, confirming its malicious intent.

Machine Learning

Nyx PDF Classifier malicious score 0.9999

Heuristics 7

Launch action critical PDF_LAUNCH

PDF contains a /Launch action whose target is an executable, URL, or UNC path — can start an external application
VBScript-style decimal byte array decodes to a PE payload critical PDF_VBS_DECIMAL_ARRAY_PE_PAYLOAD

PDF comment text contains a VB/VBScript-style decimal byte array, such as c(077),c(090), that decodes to a verified Windows PE executable. The rule is gated on a comment-line Array(c(...)) assignment and a valid MZ/PE header to keep false positives low.
/Launch action target: cmd.exe critical PDF_LAUNCH_COMMAND

PDF /Launch action specifies an executable target with parameters '/c echo Set fso=CreateObject("Scripting.FileSystemObject"' — references a known-dangerous executable (cmd, PowerShell, etc.).
ClamAV: Win.Trojan.Dropper-132 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Win.Trojan.Dropper-132
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 script payload in PDF stream high PDF_EMBEDDED_SCRIPT_PAYLOAD

PDF stream bytes contain script execution markers such as ActiveXObject/CreateObject, WScript.Shell, PowerShell, or shell-exec primitives. This is stronger than ordinary PDF JavaScript because it indicates a staged external script payload hidden in stream bytes.
Suspicious extracted artifact medium 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_pdf_script_0003cc93.bin` `254e055144dfc4a9a2397ba61d986921ae80ec817787ca53a224b4aaef4b3f74`	pdf-embedded-script	PDF raw stream script payload at offset 0x3CC93	248958 bytes
Detection ClamAV: Win.Trojan.Dropper-133 Obfuscation or payload: likely Carved artifact contains 2 shell/COM execution token(s).
`decimal_array_pdf_pe_00000229.exe` `fc780efe356258258a01f4ef29e7842b82bd048555a8137a70fe030de04ff0ac`	embedded-pe	PDF raw comment decimal-array PE payload at offset 0x229	35205 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.77, consistent with packed or encrypted content.

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