PDF malware analysis — malicious · 733f38a9c3dde52c

MALICIOUS

PDF

11.0 KB Created: 2010-07-31 23:47:54 +04:00 Authoring application: n_Dv_MF (via 0a2a51)

MD5: 231fc7f1300d2e6f94bccfaddbd98ea2 SHA-1: 2b65f8b21bb8e7d9743df612937b29859bb609e8 SHA-256: 733f38a9c3dde52c829c7a22609cb5e84500899a9d263b7601eb5c6c2409e989

224 Risk Score

Malware Insights

MITRE ATT&CK

T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The PDF file contains embedded JavaScript that utilizes eval() and String.fromCharCode() functions, indicating obfuscation and potential exploit code. The script `javascript_obj0011_000.js` decodes hex strings into characters, and `javascript_obj0013_001.js` extracts the last two characters of each word on the page. These are then XORed with a key in `javascript_obj0015_002.js` and executed via `app.doc.eval()`. This chain of operations strongly suggests the PDF is designed to exploit a vulnerability to download and execute a second-stage payload, as also indicated by the ClamAV detection of 'Pdf.Dropper.Agent-7272527-0'.

Machine Learning

Nyx PDF Classifier malicious score 0.9998

Heuristics 8

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.Dropper.Agent-7272527-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Dropper.Agent-7272527-0
eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
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)
Optional Content Group with action trigger low PDF_OPTIONAL_CONTENT

Optional Content Group (layer) co-occurs with an action trigger — content can be selectively hidden from viewers or scanners while the action still fires on open
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 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0011_000.js` `dc705876750eed4e4eb27b4163de9c561ab2d4bc74485d590fbb7b87a9a7d354`	pdf-javascript-stream	PDF /JS object 11 at offset 0x24B7	511 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).
`javascript_obj0013_001.js` `bcba5e4f4026cf2279324908a65bb249ef15e48842db1a8f6f43f01a549eab64`	pdf-javascript-stream	PDF /JS object 13 at offset 0x261D	193 bytes
`javascript_obj0015_002.js` `eb2e4375753e7b3a5bfa4cce27406cd561075bb767f1af69229bc25dba91f42d`	pdf-javascript-stream	PDF /JS object 15 at offset 0x271E	45 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).

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