PDF malware analysis — malicious · 7731a5f7521e804f

MALICIOUS

PDF

3.2 KB

MD5: 25d407d6ae33bf0c00ef7db05851d21b SHA-1: a1f9fa16495a4d242bf1005673d607e90499dabf SHA-256: 7731a5f7521e804f6861df9010346366c0761b35ab79d4da8334383e664716a2

270 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

This PDF contains embedded JavaScript that attempts to write a PE payload to disk as 'helpme.exe' and then execute it using 'cmd.exe /c helpme.exe'. The PDF also contains a direct launch action targeting 'cmd.exe', reinforcing the execution intent. The script's decimal array decodes to a PE payload, indicating a downloader or dropper functionality.

Machine Learning

Nyx PDF Classifier malicious score 0.9998

Heuristics 5

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 — references a known-dangerous executable (cmd, PowerShell, etc.).
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_0000050c.bin` `ce41485e8df28bdb45b1fb3a020bb96a00a006cbdf0aa1d036e57307efe56b9d`	pdf-embedded-script	PDF raw stream script payload at offset 0x50C	1105 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 shell/COM execution token(s).
`decimal_array_pdf_pe_00000224.exe` `e294cabee9f04e14b71574e8e5e2f286a944849888f80d0bdac5ca129e28b5fc`	embedded-pe	PDF raw comment decimal-array PE payload at offset 0x224	133 bytes

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