The Group-IB Threat Intelligence team has identified HOLLOWGRAPH, a new malware sample that we attribute, with high confidence, to the Cavern backdoor framework. This malware is one component of a larger toolkit, and it uses the Microsoft Graph API through a compromised Microsoft 365 account observed in Israel to communicate with its operators — a technique that helps conceal command-and-control traffic within legitimate Microsoft 365 communications.
The malware supports just two commands, get and send, and executes both exclusively through trusted Microsoft cloud infrastructure. Using the Microsoft Graph API, it treats the compromised mailbox’s calendar as a two-way dead-drop: operators plant tasking as calendar events, and the implant exfiltrates stolen files by creating its own events with encrypted data attached. To avoid catching the mailbox owner’s attention, every event is dated far into the future — 13 May 2050 — with payloads attached as files to the event.
Read more…
Source: Group-IB
Sign up for the Cyber Security Review Newsletter
The latest cyber security news and insights delivered right to your inbox
Related:
- X.509 metadata can carry information through the firewall
February 6, 2018
A security researcher, who last year demonstrated that X.509 certificate exchanges could carry malicious traffic, has now published his proof-of-concept code. Fidelis Cybersecurity’s Jason Reaves has disclosed a covert channel that uses fields in X.509 extensions to sneak data out of corporate networks. The X.509 standard defines the characteristics of public key certificates, and anchors much of ...
- Meltdown-Spectre: Malware is already being tested by attackers
February 1, 2018
German antivirus testing firm AV-Test has identified 139 samples of malware that seem to be early attempts at exploiting the Meltdown and Spectre CPU bugs. “So far, the AV-Test Institute discovered 139 samples that appear to be related to recently reported CPU vulnerabilities. CVE-2017-5715, CVE-2017-5753, CVE-2017-5754,” the company wrote on Twitter. The company has posted SHA-256 hashes of several ...
- Ransomware: Is time running out for the biggest menace on the web?
January 26, 2018
Ransomware attacks like WannaCry and Petya caused major chaos last year, while the likes of Locky and Cerber were less high-profile, but still managed to generate large amounts of income for their criminal creators. 2017 was the year of ransomware, but it could be that the file-encrypting malware has already reached its peak, as an analysis of cybercriminal campaigns appears to show that malicious ...
- Satori Author Linked to New Mirai Variant Masuta
January 23, 2018
Researchers at NewSky Security say the hacker behind a Mirai malware variant called Satori, also known as Mirai Okiru, is the same hacker behind two new Mirai variants called Masuta and PureMasuta. Based on source code for Masuta malware recently found on the dark web, researchers at NewSky Security said they were able to connect the ...
- Triple Meltdown: How So Many Researchers Found A 20-Year-Old Chip Flaw At The Same Time.
January 7, 2018
On a cold Sunday early last month in the small Austrian city of Graz, three young researchers sat down in front of the computers in their homes and tried to break their most fundamental security protections. Two days earlier, in their lab at Graz’s University of Technology, Moritz Lipp, Daniel Gruss, and Michael Schwarz had determined to ...
- Kernel-memory-leaking Intel processor design flaw forces Linux, Windows redesign
January 2, 2018
A fundamental design flaw in Intel’s processor chips has forced a significant redesign of the Linux and Windows kernels to defang the chip-level security bug. Programmers are scrambling to overhaul the open-source Linux kernel’s virtual memory system. Meanwhile, Microsoft is expected to publicly introduce the necessary changes to its Windows operating system in an upcoming Patch ...