RTF malware analysis — malicious · ef65d9f88f9c943e

MALICIOUS

RTF

381.9 KB First seen: 2020-05-25

MD5: faa2d021667d640d11ad31e15a96618c SHA-1: 37d4604f39f10833dfb7c69baa148f536a370f8b SHA-256: ef65d9f88f9c943e0aac588c272e96f3456cfa8862661fb898e92fdd2bd15bed

242 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 exploits the CVE-2017-11882 vulnerability in Microsoft Equation Editor. This exploit is known to download and execute a second-stage payload, indicated by the 'RTF_EQUATION_EDITOR' and 'CVE_2017_11882_RELATED' heuristic firings. The ClamAV detection 'Rtf.Dropper.Agent-7702135-0' further confirms its malicious nature as a dropper.

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.
ClamAV: Rtf.Dropper.Agent-7702135-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Rtf.Dropper.Agent-7702135-0
\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.
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_off000007aa.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x7AA	194509 bytes
SHA-256: `8d70fce8eaf058d7d852e53496d758e69978377ef6fec1a1b0d4d818a47730cb`
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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