Malicious PDF — malware analysis report

Static analysis result for SHA-256 a24bdb329c609794…

MALICIOUS

PDF

238.1 KB Created: 2017-11-18 16:15:13 Authoring application: Joomla! 1.5 - Open Source Content Management (via TCPDF 2.5.000_PHP4 (http://www.tcpdf.org))
MD5: 2addb44277f83e5f5be9a26a9baad7af SHA-1: b7ac1b731f6492c84de4d355cb94acb72088eb22 SHA-256: a24bdb329c6097949ca5b23b156288b499753be874d48a2cda48d233d90832ca
120 Risk Score

Malware Insights

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

The PDF was flagged by multiple heuristics, including a critical ClamAV detection for 'Pdf.Dropper.Agent-7288759-0' and a high ML classifier score. The presence of an embedded script payload and the 'FROMCHARCODE' heuristic suggest an attempt to obfuscate malicious code, likely for delivering a secondary payload. The ML classifier's high confidence score further supports the malicious nature of this PDF.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9504

Heuristics 4

  • ClamAV: Pdf.Dropper.Agent-7288759-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Dropper.Agent-7288759-0
  • Embedded script payload in PDF stream medium PDF_EMBEDDED_SCRIPT_PAYLOAD
    PDF stream bytes contain an HTML/XFA <script> tag without accompanying Windows shell-execution primitives — common in accessible XFA forms but worth surfacing for analyst review.
  • String.fromCharCode low PDF_FROMCHARCODE
    String.fromCharCode found — used to construct payload strings dynamically. Common in benign JavaScript libraries for codepoint manipulation, so this alone is informational; weaponised use is also caught by the dedicated fromCharCode-stage and exploit-shape rules.
  • 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.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
stream_002_off0000b783.bin
a5337ef1f5a0dfe4dc8fa6b4f3ef847a53624800b5928a0eeef5b888ceecaabc
decompressed-pdf-stream PDF FlateDecoded stream at offset 0xB783 264072 bytes
embedded_pdf_script_0003a937.bin
79967e88bca394c4fc992e6fc2aad580dfa6bb8b00a946458f8decfd07343849
pdf-embedded-script PDF decompressed stream script payload at offset 0x3A937 243782 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).