PDF malware analysis — malicious · fb51688b5977917a

MALICIOUS

PDF

32.3 KB

MD5: 869d5a9230397f00a7012746fc0c3e87 SHA-1: e6ddcaf09864061aa3937a36e6203a399dfc0c92 SHA-256: fb51688b5977917a62537b773d89d8efef291f42c6d679d23bddd03ae05aa244

134 Risk Score

Malware Insights

MITRE ATT&CK

T1566.002 Phishing: Spearphishing Attachment

The PDF contains obfuscated JavaScript, identified as a multi-stage dropper. This script is designed to download and execute a second-stage payload, as indicated by the 'PDF_JS_OBFUSCATED_DROPPER' heuristic. The presence of anti-analysis checks like 'repeated_pluginschk' further suggests malicious intent. ClamAV detection confirms its malicious nature.

Heuristics 7

ClamAV: Pdf.Exploit.Agent-21217 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Pdf.Exploit.Agent-21217
Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER

PDF JavaScript shows 3 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, 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.
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.
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_obj0007_000.js` `f6c97065fa889619cb9a29fe74bbdc6f16ab91ffdbea8e9485e055c68a189b7a`	pdf-javascript-stream	PDF /JS object 7 at offset 0x149	443 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).
`deobfuscated.js` `3a64e42bc6d8da24cd729e916f9ac878e4b351261c6c4b3c91d374b392a2980d`	deobfuscated-js	PDF JavaScript deobfuscation pass	596 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).

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