Malicious RTF — malware analysis report

Static analysis result for SHA-256 5ddfcee976daf1f7…

MALICIOUS

RTF

864.6 KB First seen: 2022-09-26
MD5: 027e492f7ceb4cf8023d311602434de3 SHA-1: 5b5a739f5688ce1154a2a4af2de1e9db8854294d SHA-256: 5ddfcee976daf1f71a8b1f41a4dd170e80683b2e79d48e312d6010f941de148f
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains embedded OLE objects and specifically triggers the CVE-2017-11882 vulnerability through the Equation Editor. This indicates the file is designed to exploit this known vulnerability for initial execution. The embedded OLE object data, when decoded, contains what appears to be VBScript code intended to read configuration strings from an INI file, likely to download and execute a secondary payload.

Heuristics 5

  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger 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.
  • 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

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000012ab.bin
d69363265cbc859b24c20c6507c7ab9a97b5586ee6bf525b6cacc9bf114edbc1		 rtf-objdata-decoded RTF \objdata at offset 0x12AB 81409 bytes
objdata_01_off0002f038.bin
d541f40d3697d40fb5a5ae03df885a1ecc9c95b0c0f7dd7bfe86e66ff4cfbf9a		 rtf-objdata-decoded RTF \objdata at offset 0x2F038 141506 bytes

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