PDF malware analysis — malicious · 645f7d2d166e23c3

MALICIOUS

PDF

244.6 KB

MD5: a99fe14ad9fc55df86976686407cf265 SHA-1: 53efc4698d59fd7d1f25d20bdfa396bd6e8da082 SHA-256: 645f7d2d166e23c342e30527ffc9a4ad7454c96b5caa01be59328ac40f54e67c

390 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

This PDF contains an embedded script that decodes a decimal byte array into a PE payload, identified as a trojan dropper. The PDF also has a launch action that executes 'cmd.exe' with parameters that appear to be part of a script to facilitate the execution of the dropped payload. The embedded script's intent is to download and execute a second-stage payload.

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` `3e315d13265e30c8b43516fed3d7895bccd40c97cb2da0bfe1d352fc2b62c863`	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` `64e2cf333614508445657d6ae013fde89b4c5281fc649de0def3d6d4b425848a`	embedded-pe	PDF raw comment decimal-array PE payload at offset 0x229	35328 bytes
Detection ClamAV: Win.Trojan.Agent-535339 Obfuscation or payload: likely Carved artifact entropy is 7.76, consistent with packed or encrypted content.

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