Malicious PDF — malware analysis report

Static analysis result for SHA-256 4287c4e5c5ccdbba…

MALICIOUS

PDF

639.0 KB Created: A  bg÷Z(KîÎ 3Ï¢{zêdFÚû°·4(‹<þ–ñKWÕC(ßcƒ ì  ³8 Authoring application: ”°?ÝV_˜Ýk­þ.§Ë£h”<$oƘ-=}ŽN‡®y‡ G•"¤œ*š (via 5nD³Aõì?Oó¿¥Èѯ&/ZVœµŒ¼õýÚ³]¨«°Bëð;ÑzUf)
MD5: 26be3191fb17e6b25b66d918a4255d0c SHA-1: 940e26f08d7f23317873399ca37551ba36979868 SHA-256: 4287c4e5c5ccdbbacfa505f78770a008f0ebc7dafaaff0fe2f3176460c06df4b
104 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1566.002 Spearphishing Attachment

The sample is a PDF file flagged as malicious by an ML classifier. It contains embedded JavaScript and is encrypted, with the JavaScript referencing the encrypted content, indicating an attempt to conceal a malicious payload. The presence of PDF_JAVASCRIPT and PDF_ENCRYPTED_WITH_JS heuristics strongly suggests that the embedded JavaScript is used to decrypt and execute the malicious content. No specific IOCs were extracted, but the techniques indicate a downloader or exploit delivery mechanism.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9979

Heuristics 6

  • Encrypted PDF carries /JavaScript — payload hidden from static analysis high PDF_ENCRYPTED_WITH_JS
    PDF declares /Encrypt and also references an executable trigger (/JavaScript). Document encryption hides the JavaScript body and stream contents from static scanners — combined with auto-execution indicators this is a known evasion pattern used to deliver weaponised JavaScript that the analyst cannot inspect without the decryption key.
  • 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.
  • 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.
  • Embedded file low PDF_EMBEDDED
    PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload
  • XFA form low PDF_XFA
    PDF uses XML Forms Architecture — can contain script logic
  • PDF paints image(s) but contains no text operators info PDF_IMAGE_ONLY_LURE
    PDF has 1 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.