Malicious PDF — malware analysis report

Static analysis result for SHA-256 11bb73bf35f5b497…

MALICIOUS

PDF

55.1 KB
MD5: 935ecaed76682561d128cd61930a9dd1 SHA-1: 6c4cc8527ac2d5bf14c952d7d990c59c60fc338f SHA-256: 11bb73bf35f5b49759caa61ff2ef41630adf666720c4818876b6a1e4dbf7e483
330 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The PDF file contains embedded scripts and a launch action that executes cmd.exe, indicating an attempt to download and run a secondary payload. The embedded script, which decodes a PE payload, and the critical PDF_LAUNCH_COMMAND heuristic strongly suggest this malicious behavior. The ClamAV detection further supports the malicious nature of the extracted artifact.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9971

Heuristics 6

  • 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 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.

FilenameKindSourceSize
embedded_pdf_script_0003cc93.bin
3e315d13265e30c8b43516fed3d7895bccd40c97cb2da0bfe1d352fc2b62c863
pdf-embedded-script PDF decompressed stream script payload at offset 0x3CC93 248958 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
64e2cf333614508445657d6ae013fde89b4c5281fc649de0def3d6d4b425848a
embedded-pe PDF decompressed stream comment decimal-array PE payload at offset 0x229 35328 bytes
Detection
ClamAV: Win.Trojan.Agent-535339
Obfuscation or payload: likely
Carved artifact entropy is 7.76, consistent with packed or encrypted content.