I published the following diary on isc.sans.edu: “XLSB Files: Because Binary is Stealthier Than XML“: In one of his last diaries, Brad mentioned an Excel sheet named with a .xlsb extension. Now, it was my turn to find one… What’s the magic behind this file extension? “XLS” means that we
I published the following diary on isc.sans.edu: “Excel Recipe: Some VBA Code with a Touch of Excel4 Macro“: Microsoft Excel supports two types of macros. The legacy format is known as “Excel4 macro” and the new (but already used for a while) is based on VBA. We already cover both
I published the following diary on isc.sans.edu: “Malicious PowerPoint Add-On: ‘Small Is Beautiful‘”: Yesterday I spotted a DHL-branded phishing campaign that used a PowerPoint file to compromise the victim. The malicious attachment is a PowerPoint add-in. This technique is not new, I already analyzed such a sample in a previous
I published the following diary on isc.sans.edu: “Spotting the Red Team on VirusTotal!“: Many security researchers like to use the VirusTotal platform. The provided services are amazing: You can immediately have a clear overview of the dangerousness level of a file but… VirusTotal remains a cloud service. It means that, once you uploaded a
I published the following diary on isc.sans.edu: “VBA Macro Trying to Alter the Application Menus‘”: Who remembers the worm Melissa? It started to spread in March 1999! In information security, it looks like speaking about prehistory but I spotted a VBA macro that tried to use the same defensive technique
I published the following diary on isc.sans.edu: “New Example of XSL Script Processing aka ‘Mitre T1220‘”: Last week, Brad posted a diary about TA551. A few days later, one of our readers submitted another sample belonging to the same campaign. Brad had a look at the traffic so I decided
I published the following diary on isc.sans.edu: “How Attackers Brush Up Their Malicious Scripts“: On Friday, I received a bunch of alerts from one of my YARA hunting rules. Several samples were submitted from the same account (through the VT API), from the same country (US), and in a very
I published the following diary on isc.sans.edu: “A Mix of Python & VBA in a Malicious Word Document“: A few days ago, Didier wrote an interesting diary about embedded objects into an Office document. I had a discussion about an interesting OLE file that I found. Because it used the same
I published the following diary on isc.sans.edu: “Malicious Excel Sheet with a NULL VT Score“: Just a quick diary today to demonstrate, once again, that relying only on a classic antivirus solution is not sufficient in 2020. I found a sample that just has a very nice score of 0/57 on VT. Yes, according to
I published the following diary on isc.sans.edu: “A Safe Excel Sheet Not So Safe“: I discovered a nice sample yesterday. This excel sheet was found in a mail flagged as “suspicious†by a security appliance. The recipient asked to release the mail from the quarantine because “it was sent from
