RTF malware analysis — malicious · dc274e49e61e0e29

MALICIOUS

RTF

2.66 MB First seen: 2021-06-30

MD5: b505c760b0a17405af69b2332b1db3da SHA-1: 56fffdbba296ea7a455945a78e85b07aa0b9f555 SHA-256: dc274e49e61e0e299fc6a3164e92d5ed124acacb5c3df36aacfdd5ac698a53ad

242 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains multiple indicators of exploitation for CVE-2017-11882, specifically through an embedded Equation Editor OLE object. This object's native payload is decoded and exhibits high entropy, strongly suggesting it is a packed or encrypted second-stage executable. The presence of ".objupdate" further indicates an attempt to force OLE object activation, leading to payload execution.

Heuristics 7

Split hex Equation Editor ProgID + OLE object critical CVE likely 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.
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 ~2791KB 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
Embedded OLE object medium RTF_OBJEMB

RTF contains \objemb — embedded OLE object
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_off000000a3.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xA3	1395668 bytes
SHA-256: `13019a6d5effaf4232fba3414b44c7a67530b37e1682ebf1c96905412369e52b`
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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