Malicious PDF — malware analysis report

Static analysis result for SHA-256 63186806f5ab6e6d…

MALICIOUS

PDF

44.9 KB
MD5: 43d9c5ee535e8e74ff1d2de8d44657ff SHA-1: b53c45fe8506fa91ea00b547437dd4d6ca5f40a7 SHA-256: 63186806f5ab6e6d92b2604fbaa968a6783841404d9519d3e87b5d66081419a1
166 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is a PDF file flagged as malicious by ClamAV and an ML classifier. It contains embedded JavaScript streams that are heavily obfuscated but appear to be designed to execute code. The primary function of the JavaScript is likely to download and execute a secondary payload, a common technique for initial compromise.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9999

Heuristics 4

  • ClamAV: Pdf.Exploit.Agent-36128 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-36128
  • 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.
  • 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.

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0008_000.js
0f45cf4d71fcd2ecd2b5999d1f8d7b64c6a48ff65897f6207373031c1f842b21		 pdf-javascript-stream PDF /JS object 8 at offset 0x1E7 45221 bytes
javascript_obj0008_001.js
5e69ff88160ebcee0c9bb072df626b31adc5a61b1b7c493b7afba674071d33ca		 pdf-javascript-stream PDF /JS object 8 at offset 0x20A 45471 bytes
Detection
ClamAV: Pdf.Exploit.Agent-36128
Obfuscation or payload: unlikely
legacy_pdfkit_stage_000.js
a05e61a961eb718c99ae38e96442c952b1e84ac7c987d012a68dd904c5109f8b		 deobfuscated-js double percent-decoded annotation JavaScript at offset 0x1E7 32987 bytes

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