Malicious PDF — malware analysis report

Static analysis result for SHA-256 59bd4424f3d72144…

MALICIOUS

PDF

59.8 KB
MD5: 598349fbcecb08f1b150242f54417dfe SHA-1: 7f3bf72e932ef130ee9b04a3c7c69ec5bdd41f41 SHA-256: 59bd4424f3d72144f5ce27d9b2854f6984a50b874f6107926c849aab0df81978
286 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File

The PDF file contains embedded JavaScript that utilizes `eval()` and `unescape()` functions, indicating obfuscated code execution. This script is likely responsible for downloading and executing a second-stage payload, as suggested by the 'Pdf.Exploit.Agent-35955' ClamAV detection and the presence of an extracted JavaScript file named 'legacy_pdfkit_stage_000.js'. The high heuristic scores for PDF_JAVASCRIPT, PDF_JS, PDF_RICHMEDIA, PDF_EVAL, and PDF_UNESCAPE further support this conclusion. The embedded file 'embedded_file_obj0003.bin' is also suspicious.

Heuristics 11

  • ClamAV: Pdf.Exploit.Agent-35955 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-35955
  • 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.
  • RichMedia (Flash) high PDF_RICHMEDIA
    PDF contains /RichMedia (Adobe Flash) which is a historic exploit vector (matched inside decoded stream)
  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • unescape() call high PDF_UNESCAPE
    unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
  • ASCIIHexDecode filter (with exploit indicators) medium PDF_FILTER_HEX
    Hex-encoding filter present alongside exploit delivery indicators — often used to hide payload or shellcode bytes
  • 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
  • Suspicious extracted artifact info 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.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/xap/1.0/
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/AcrobatAdhocWorkflow/1.0/

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
embedded_file_obj0003.bin
b52b546f445164350b564869980b2766408aef84eb0be15a0893d30d2249d32f
pdf-embedded-file PDF EmbeddedFile object 3 at offset 0xE29 26804 bytes
Detection
ClamAV: Pdf.Exploit.Agent-35955
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.
legacy_pdfkit_stage_000.js
a6a68cec92c9ff48318a37483a59e2a964f15a3a86cc6c540ba4da0f3673d267
deobfuscated-js repeated-marker hex decoded JavaScript at offset 0x650 383 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
objstm_0019_00.bin
ad3182cffbb82c0409b4de6a4edb4839ac92eccfa84fc7af089bab0d9b25c07a
pdf-objstm-decoded PDF /ObjStm 19 0 obj (inflated) 6742 bytes