DirtyMoe botnet infected 100,000+ Windows systems in H1 2021
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2020-0674 | Use-After-Free RCE in Microsoft Internet Explorer Scripting Engine CVE-2020-0674 is a use-after-free memory corruption flaw (CWE-416) in the way the Internet Explorer scripting engine handles objects in memory, distinct from a series of sibling scripting-engine RCEs fixed at the same time (CVE-2020-0673, 0710, 0711, 0712, 0713, 0767). Triggering it requires user interaction: an attacker must convince a user to view a specially crafted web page (for example via a phishing link or malicious web content) while it renders in Internet Explorer, and the mishandled memory then allows code execution under the high-complexity, network-reachable conditions reflected in the CVSS vector (AV:N/AC:H/UI:R). Successful exploitation gives the attacker remote code execution with the privileges of the logged-in user, so the practical risk is highest for users browsing with Internet Explorer on Windows, including IE 8 through IE 11 targeted by the public exploits. Exploitation is confirmed in the wild: Microsoft warned of the flaw as an unpatched zero-day being used in targeted attacks before its February 2020 Patch Tuesday fix, public PoC/exploit code is available (including a working exploit for IE 8-11), the Magnitude exploit kit referenced in coverage used it as a delivery vector, and CISA added it to the Known Exploited Vulnerabilities catalog on 2021-11-03 alongside a very high EPSS score (86.9% probability of exploitation in 30 days, 100th percentile). The required remediation is to apply the Microsoft security updates from February 2020 that address this CVE. Do: Apply the Microsoft February 2020 Patch Tuesday security updates that fix CVE-2020-0674 on all Windows endpoints and servers, prioritizing per the CISA KEV required action. Until patched, limit Internet Explorer use to trusted sites and consider Microsoft's suggested mitigations (such as restricting active scripting); note that third-party micropatches existed that emulated the vendor workaround without its usability side effects. After patching, verify IE11 remediation status across the estate and, where feasible, retire Internet Explorer usage entirely to reduce exposure to this recurring scripting-engine bug class. | 7.5 | 87% | KEV PoC ×4 |
| masshundreds of millions of Windows endpoints (IE 11 was bundled with every supported Windows release at disclosure) |
Full article435 words · extracted from securityaffairs.com · click to collapse
DirtyMoe is a Windows botnet that is rapidly growing, it passed from 10,000 infected systems in 2020 to more than 100,000 in the first half of 2021.
Researchers from Avast are warning of the rapid growth of the DirtyMoe botnet (PurpleFox, Perkiler, and NuggetPhantom), which passed from 10,000 infected systems in 2020 to more than 100,000 in the first half of 2021. Experts defined DirtyMoe as a complex malware that has been designed as a modular system.
The Windows botnet has been active since late 2017, it was mainly used to mine cryptocurrency, but it was also involved in DDoS attacks in 2018. The DirtyMoe rootkit was delivered via malspam campaigns or served by malicious sites hosting the PurpleFox exploit kit that triggers vulnerabilities in Internet Explorer, such as the CVE-2020-0674 scripting engine memory corruption vulnerability.
The operations behind the DirtyMoe botnet rapidly changed since the end of 2020, when the malware authors added a worm module that could increase their activity by spread via the internet to other Windows systems.
“Recently, a new infection vector that cracks Windows machines through SMB password brute force is on the rise” reads the analysis published by AVAST.
The module that implements the warm capabilities was spotted scanning the internet and performing password brute-force attacks against Windows systems with SMB port open online.
“The increase of incidences has been higher in orders of magnitude this year, as the logarithmic scale of Figure 3 indicates.” continues the report.
Most of the hits are in Russia (65k), followed by Ukraine, Vietnam and Brazil.
Experts pointed out that the number of infected systems could be far greater because data provided by AVAST are only related to systems running their antivirus solution.
Most of the C&C servers involved in the attacks are located in China, a circumstance that suggests that the threat actors behind DirtyMoe are a well-organized group that operates on a global scale.
“The malware implements many self-defense and hiding techniques applied on local, network, and kernel layers. Communication with C&C servers is based on DNS requests and it uses a special mechanism translating DNS results to a real IP address. Therefore, blocking of C&C servers is not an easy task since C&C addresses are different each time and they are not hard-coded.” concludes the analysis.” continues the analysis. “Both PurpleFox and DirtyMoe are still active malware and gaining strength.”
Avast published indicators of compromise (IOCs) related to the attacks that involved this botnet
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