PDF malware analysis — malicious · 14b74cabc6a1bc4b

MALICIOUS

PDF

243.6 KB

MD5: 90426836509c306afa294b13fbfb9111 SHA-1: 5bc4b0637171c8727cd5f9c913ac8872f97a9f2b SHA-256: 14b74cabc6a1bc4b120bd517e78098c5061d6d3878edd2eb56e24ce9545e2805

390 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

This PDF file exhibits multiple critical heuristic firings indicating malicious intent. It contains a launch action that executes cmd.exe, which is used to decode a decimal byte array into a PE payload. This payload, identified by SHA256 hash 2c1fd42f86f759c5599b435df8e7e1b90560f3ab61e84f28dfd114e2b60e3b69, is likely a second-stage malware dropper. The embedded script, though partially obfuscated, contains byte array decoding logic consistent with this dropper behavior.

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_0003c86d.bin` `3da226a5e909238e7ef52e724178cf3cbbd0454ffc4c3d3617300962507ca264`	pdf-embedded-script	PDF raw stream script payload at offset 0x3C86D	247896 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` `2c1fd42f86f759c5599b435df8e7e1b90560f3ab61e84f28dfd114e2b60e3b69`	embedded-pe	PDF raw comment decimal-array PE payload at offset 0x229	35177 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.76, consistent with packed or encrypted content.

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