RTF malware analysis — malicious · ac913cf8fc7fb6a7

MALICIOUS

RTF

1.13 MB First seen: 2023-09-20

MD5: 9e48278fd8663c2722eb3ce7b5ae34e7 SHA-1: daf4ea109d2fdaff37b9c777aa7082a8087082e9 SHA-256: ac913cf8fc7fb6a7f7b35a51b63016ea29282e37cfec581a82668e50871a5ccf

222 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1559.001 Component Object Model

The RTF document contains OLE object data, specifically a decoded Equation Editor payload. Heuristics indicate a critical vulnerability related to CVE-2017-11882, suggesting the file is designed to exploit this flaw for initial execution. The presence of a large, high-entropy embedded artifact further supports the delivery of a secondary payload.

Heuristics 6

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.
Decoded Equation Editor payload + PE critical 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.
\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 ~1180KB 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_off00000088.bin` `bdc842ddecc739d637c9dc497ea8eb23bbeef579c305b3f9c3f2f68c15005c37`	rtf-objdata-decoded	RTF \objdata at offset 0x88	590282 bytes
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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