RTF / .DOC malware analysis — malicious · 0af844289326cb49

MALICIOUS

RTF / .DOC

1.49 MB First seen: 2021-11-07

MD5: 9a4bf2cbc9514f631d074b05cab839ec SHA-1: 7f23be8055288e44c4c6f4c77bc58ac92b699fb9 SHA-256: 0af844289326cb491b0866a62324f06a27ba45e314f0368092205c9631de3145

222 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF document contains an embedded OLE object that exploits CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. The object's native payload is large and has high entropy, indicating it likely contains a second-stage executable. The presence of ".objdata" sections and the "\objupdate" directive further support the exploitation of OLE object activation for code execution.

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.
Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR

RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
\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 ~1555KB of hex-encoded data inside \objdata sections — may hide a payload
OLE object data medium RTF_OBJDATA

RTF contains 2 \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_off00001ae1.bin` `7e22325522e9c5c855f71286bed94ddc098a4186142258ed91c54b792905c62b`	rtf-objdata-decoded	RTF \objdata at offset 0x1AE1	777844 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 8.00, consistent with packed or encrypted content.

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