Malicious PDF — malware analysis report

Static analysis result for SHA-256 89711385515c8e95…

MALICIOUS

PDF

2.2 KB
MD5: 05ccc0b9405e3f119efc595bde1a7c72 SHA-1: cb60d0781ad8389598bbe2c0b8005109c7f14afb SHA-256: 89711385515c8e955a69da21b7d1cc9607ef9a8ce0529f5d8f9d25ad064dc85e
298 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution

The PDF file contains obfuscated JavaScript that utilizes eval() and unescape() functions, indicative of exploit code. This script is designed to download and execute a second-stage payload from the URL http://simariko.com/sosisko/l.php?i=5. The presence of exploit cluster heuristics and ClamAV detection strongly supports this malicious intent.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 10

  • PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER
    PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
  • ClamAV: Pdf.Exploit.Agent-36082 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-36082
  • 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)
  • PDF exploit shellcode contains an embedded download URL high PDF_JS_SHELLCODE_DOWNLOAD_URL
    Decoded PDF exploit shellcode contains a hardcoded http(s) URL — stored as little-endian %uXXXX Unicode escapes, or hex-encoded in a document metadata field (/CreationDate, /Title) and referenced from the decoded script. Reader exploit shellcode embeds the second-stage fetch URL this way and pulls it down with a urlmon/URLDownloadToFile-style download-and-execute (commodity downloader behaviour rather than a specific Acrobat CVE).
  • 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.
  • 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. (matched inside decoded stream)
  • 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://simariko.com/sosisko/l.php?i=5

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj111611_000.js
772da696bdb365f3f1eb4ea6af881baad391be62f3591b19f2f9827fcc4c9b53
pdf-javascript-stream PDF /JS object 111611 at offset 0x7E4 479 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 3 eval/decoder/string-building token(s).
legacy_pdfkit_stage_000.js
57ef02d90ddac71315ce05ce7cf0ccb19ab53cc6743cf17d7051613dc413d7e0
deobfuscated-js repeated-marker hex decoded JavaScript at offset 0x189 2834 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 3 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).