Didier Stevens

Monday 16 October 2017

Update: oledump.py Version 0.0.29

Filed under: My Software,Update — Didier Stevens @ 0:00

This new version of oledump adds support to decode strings like UNICODE strings (-t), and can dump strings (-S).

oledump_V0_0_29.zip (https)
MD5: 7F98DB95E0E9FF645B8411F421387214
SHA256: E00567490A48A7749DF07F0E7ECD8FD24B3C90DC52E18AFE36253E0B37A543C5

Sunday 15 October 2017

Overview of Content Published In September

Filed under: Announcement — Didier Stevens @ 16:09

Here is an overview of content I published in September:

Blog posts:

YouTube videos:

SANS ISC Diary entries:

NVISO Blog posts:

Sunday 8 October 2017

Quickpost: Mimikatz DCSync Detection

Filed under: Hacking,Networking,Quickpost — Didier Stevens @ 22:40

Benjamin Delpy/@gentilkiwi’s Brucon workshop on Mimikatz inspired me to resume my work on detecting DCSync usage inside networks.

Here are 2 Suricata rules to detect Active Directory replication traffic between a domain controller and a domain member like a workstation (e.g. not a domain controller):


alert tcp !$DC_SERVERS any -> $DC_SERVERS any (msg:"Mimikatz DRSUAPI"; flow:established,to_server; content:"|05 00 0b|"; depth:3; content:"|35 42 51 e3 06 4b d1 11 ab 04 00 c0 4f c2 dc d2|"; depth:100; flowbits:set,drsuapi; flowbits:noalert; reference:url,blog.didierstevens.com; classtype:policy-violation; sid:1000001; rev:1;)
alert tcp !$DC_SERVERS any -> $DC_SERVERS any (msg:"Mimikatz DRSUAPI DsGetNCChanges Request"; flow:established,to_server; flowbits:isset,drsuapi; content:"|05 00 00|"; depth:3; content:"|00 03|"; offset:22 depth:2; reference:url,blog.didierstevens.com; classtype:policy-violation; sid:1000002; rev:1;)

Variable DC_SERVERS should be set to the IP addresses of the domain controllers.

The first rule will set a flowbit (drsuapi) when DCE/RPC traffic is detected to bind to the directory replication interface (DRSUAPI).

The second rule will detect a DCE/RPC DsGetNCChanges request if the flowbit drsuapi is set.

 

These rules were tested in a test environment with normal traffic between a workstation and a domain controller, and with Mimikatz DCSync traffic. They were not tested in a production network.


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