PDF malware analysis — malicious · eb9cefe32757fe2a

MALICIOUS

PDF

17.8 KB

MD5: cbc8e2e69e2097c8123d9df7b616fbb7 SHA-1: f49550f09c1703d341c55576bfed7aaa5ece7e98 SHA-256: eb9cefe32757fe2aa174037dabfc68a3521bfb6e6dc39baa61c457e6e1a855fb

134 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF file contains heavily obfuscated JavaScript, identified as a multi-stage dropper. The script employs anti-analysis techniques such as repeated checks on app.plugIns.length and incremental evaluation of method names. It decodes embedded hex-encoded strings using String.fromCharCode, a common technique for obfuscation. The primary function of the script is to download and execute a second-stage payload, as indicated by the 'PDF_JS_OBFUSCATED_DROPPER' heuristic. ClamAV also detected this file as 'Pdf.Exploit.Agent-35901'.

Heuristics 7

ClamAV: Pdf.Exploit.Agent-35901 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-35901
Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER

PDF JavaScript shows 4 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, hex_codec_loop, incremental_eval_build, repeated_pluginschk. This is strongly consistent with pre-2011 Adobe Reader PDF droppers — OpenAction JS reads encoded data from annotation subjects, decodes it through one or more hex / base-N loops, and invokes eval indirectly (method name built one character at a time). The actual CVE is hidden in the final decoded layer and is not visible via static analysis.
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)
syncAnnotScan annotation-staging primitive low PDF_FOXIT_SYNCANNOTSCAN

PDF JavaScript calls syncAnnotScan() — a no-op annotation-enumeration primitive used by exploit-kit JavaScript to stage payload reads from annotation /Subject fields before eval(). Not a vulnerable sink itself; rarely seen in legitimate PDFs. (matched in decompressed 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.

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0009_000.js` `4718a27c2224fc36bf24f8e8e04598f1ad78adce4401c7be2708318738a6983d`	pdf-javascript-stream	PDF /JS object 9 at offset 0x44EE	469 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`deobfuscated.js` `0a2ef896c4ad79cfd630234d9d19e5d3bfe372e2f2fdd139dcf9b21c5b096916`	deobfuscated-js	PDF JavaScript deobfuscation pass	121742 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 4 eval/decoder/string-building token(s). Carved artifact contains 2 long base64-like blob(s).

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