Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 33761ca9879abfa5…

MALICIOUS

RTF / .DOC

19.1 KB First seen: 2022-08-17
MD5: 41d0d1fab675c2c7f9ad7d8c1f11ee5f SHA-1: 7091e4320e0491623f04c6ff3f736ae5631c641f SHA-256: 33761ca9879abfa59b8bd0bef99a8e7c3dea6e3835bc54273fa14a6c04d2b9f5
180 Risk Score

Malware Insights

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

The sample is an RTF document containing an embedded OLE object that leverages the CVE-2017-11882 vulnerability in the Equation Editor. The presence of `RTF_OBJDATA`, `RTF_OBJEMB`, `CVE_2017_11882_EQUATION_OLE10NATIVE`, `RTF_OBJUPDATE`, and `RTF_OLE10NATIVE_STREAM` heuristics strongly indicates exploitation of this known vulnerability. This technique is commonly used to download and execute a second-stage payload.

Heuristics 5

  • Equation Editor Ole10Native payload — CVE-2017-11882 likely critical CVE likely CVE_2017_11882_EQUATION_OLE10NATIVE
    RTF decodes to an activated Microsoft Equation 3.0 OLE storage whose payload is a high-entropy Ole10Native stream rather than normal Equation Native/MTEF data. This is a weaponized Equation Editor RCE delivery shape consistent with CVE-2017-11882/CVE-2018-0802.
  • Ole10Native stream in RTF OLE object high CVE related RTF_OLE10NATIVE_STREAM
    RTF contains an embedded OLE object with an Ole10Native stream. This is a strong payload-container signal and is related to Word/OLE exploit delivery, but it is not specific enough on its own to assign a CVE.
  • \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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000eb1.bin
b9820fae928a5ea8fc976743b213da874e3a761a3b377d5443ddddc0874c6041
rtf-objdata-decoded RTF \objdata at offset 0xEB1 4308 bytes