A just lately patched safety vulnerability within the 7-Zip archiver software was exploited within the wild to ship the SmokeLoader malware.
The flaw, CVE-2025-0411 (CVSS rating: 7.0), permits distant attackers to avoid mark-of-the-web (MotW) protections and execute arbitrary code within the context of the present person. It was addressed by 7-Zip in November 2024 with model 24.09.
“The vulnerability was actively exploited by Russian cybercrime groups through spear-phishing campaigns, using homoglyph attacks to spoof document extensions and trick users and the Windows Operating System into executing malicious files,” Pattern Micro safety researcher Peter Girnus mentioned.
It is suspected that CVE-2025-0411 was seemingly weaponized to focus on governmental and non-governmental organizations in Ukraine as a part of a cyber espionage marketing campaign set towards the backdrop of the continued Russo-Ukrainian battle.
MotW is a safety characteristic applied by Microsoft in Home windows to stop the automated execution of recordsdata downloaded from the web with out performing additional checks by means of Microsoft Defender SmartScreen.
CVE-2025-0411 bypasses MotW by double archiving contents utilizing 7-Zip, i.e, creating an archive after which an archive of the archive to hide the malicious payloads.
“The root cause of CVE-2025-0411 is that prior to version 24.09, 7-Zip did not properly propagate MotW protections to the content of double-encapsulated archives,” Girnus defined. “This allows threat actors to craft archives containing malicious scripts or executables that will not receive MotW protections, leaving Windows users vulnerable to attacks.”
Assaults leveraging the flaw as a zero-day have been first detected within the wild on September 25, 2024, with the an infection sequences resulting in SmokeLoader, a loader malware that has been repeatedly used to focus on Ukraine.
The start line is a phishing e mail that accommodates a specially-crafted archive file that, in flip, employs a homoglyph assault to go off the interior ZIP archive as a Microsoft Phrase doc file, successfully triggering the vulnerability.
The phishing messages, per Pattern Micro, have been despatched from e mail addresses related to Ukrainian governing our bodies and enterprise accounts to each municipal organizations and companies, suggesting prior compromise.
“The use of these compromised email accounts lend an air of authenticity to the emails sent to targets, manipulating potential victims into trusting the content and their senders,” Girnus identified.
This method results in the execution of an web shortcut (.URL) file current throughout the ZIP archive, which factors to an attacker-controlled server internet hosting one other ZIP file. The newly downloaded ZIP accommodates the SmokeLoader executable that is disguised as a PDF doc.
At the least 9 Ukrainian authorities entities and different organizations have been assessed to be impacted by the marketing campaign, together with the Ministry of Justice, Kyiv Public Transportation Service, Kyiv Water Provide Firm, and Metropolis Council.
In mild of the energetic exploitation of CVE-2025-0411, customers are really helpful to replace their installations to the newest model, implement e mail filtering options to dam phishing makes an attempt, and disable the execution of recordsdata from untrusted sources.
“One interesting takeaway we noticed in the organizations targeted and affected in this campaign is smaller local government bodies,” Girnus mentioned.
“These organizations are often under intense cyber pressure yet are often overlooked, less cyber-savvy, and lack the resources for a comprehensive cyber strategy that larger government organizations have. These smaller organizations can be valuable pivot points by threat actors to pivot to larger government organizations.”
