RTF malware analysis — malicious · a5a2cfbe03d16aa9

MALICIOUS

RTF

1.26 MB First seen: 2019-12-10

MD5: 9f16bde8a5727fad503c069fbf0ece78 SHA-1: 21442db054556b547471ba73334210ba8a72f691 SHA-256: a5a2cfbe03d16aa9a5a882096113395b7e77ffc84a34c2578cb666a80153b802

222 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains an embedded OLE object that decodes to a PE file, strongly indicating exploitation of the CVE-2017-11882 vulnerability in Equation Editor. This technique is commonly used to deliver secondary payloads, suggesting the file's primary purpose is to achieve initial execution on a victim's system.

Heuristics 6

Decoded Equation Editor payload + PE critical CVE likely RTF_EQUATION_EDITOR

RTF decodes to an Equation Editor ProgID adjacent to OLE activation and the same decoded object stream contains embedded PE bytes. This matches the Equation Editor exploit surface used by CVE-2017-11882 / CVE-2018-0802 documents, while requiring payload evidence to avoid flagging benign Equation references.
Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED

RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact attribution was not recovered.
\objupdate forces OLE activation high RTF_OBJUPDATE

RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX

RTF contains ~1322KB of hex-encoded data inside \objdata sections — may hide a payload
OLE object data medium RTF_OBJDATA

RTF contains 1 \objdata section(s) — embedded OLE objects
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 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off0000006d.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x6D	661338 bytes
SHA-256: `18b71491e56a5f592a5a78140920789f421492ce5c238eef0e971e9d79b91161`
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.99, consistent with packed or encrypted content.

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