PDF malware analysis — malicious · ba784ac86a2110fd

MALICIOUS

PDF

16.3 KB

MD5: 4738c1e77cbec6f7a1db5a711d5491e4 SHA-1: 5b1ac33b69fefe5dba16820e50dab556a60c83fa SHA-256: ba784ac86a2110fd3a4bf084b227806ebc3e24a02b571262958672a2995d5639

74 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF contains obfuscated JavaScript, identified as a multi-stage dropper. This script is designed to download and execute a second-stage payload. The presence of anti-analysis checks like 'app.plugins.length' and the use of 'String.fromCharCode' indicate a deliberate attempt to evade detection. The overall attack pattern is consistent with a downloader malware.

Heuristics 6

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, hex_dashed_payload, 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 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0005_000.js` `041ad794d3db20d026f21a8e2c9d9da29721c2444af8d5467b57ae7f54e982d9`	pdf-javascript-stream	PDF /JS object 5 at offset 0x148	701 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` `9ec928ad0aeed2d7d2732eafe120b72a69d1037733bf7a64e4f8ba6a66eaf132`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1C04	12279 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).
`deobfuscated.js` `664f6848e6ea245fd083276fa6353e7258c72c93c0a21fa13b82831d035e3814`	deobfuscated-js	PDF JavaScript deobfuscation pass	106367 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 6 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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