Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 8469c124b2c7cf95…

MALICIOUS

RTF / .DOC

1.95 MB
MD5: a36ccba0c05080228c348c8846d1387c SHA-1: fefd2b22df518bc84e9a7179f8f78e6f9cf70184 SHA-256: 8469c124b2c7cf9529f96bf3f3a3b39f5bb56c5e3bd560fdabf310c025934060
180 Risk Score

Malware Insights

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

The file is an RTF document that leverages the CVE-2017-11882 vulnerability through an embedded Equation Editor object. The `RTF_EQUATION_EDITOR` and `CVE_2017_11882_ACTIVATION_RELATED` heuristics confirm this. The embedded OLE object, when activated by `RTF_OBJUPDATE`, likely executes a malicious script. The script's purpose appears to be to download and execute a second-stage payload, as indicated by the reconstructed string `eval(

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_off00001116.bin
6291386769a88acf9c7b8fe37e3173b375aade0b061f6208cf1703e7074ff3e8		 rtf-objdata-decoded RTF \objdata at offset 0x1116 25547 bytes
objdata_01_off00019175.bin
0a68d9e39a239498edad4769b15ebffc3a7aacdb0159a7082c9c85b289bc5fc1		 rtf-objdata-decoded RTF \objdata at offset 0x19175 462273 bytes

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