A just lately patched safety vulnerability within the 7-Zip archiver instrument 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 consumer. It was addressed by 7-Zip in November 2024 with model 24.09.
“The vulnerability was actively exploited by Russian cybercrime teams via spear-phishing campaigns, utilizing homoglyph assaults to spoof doc extensions and trick customers and the Home windows Working System into executing malicious recordsdata,” Pattern Micro safety researcher Peter Girnus mentioned.
It is suspected that CVE-2025-0411 was probably weaponized to focus on governmental and non-governmental organizations in Ukraine as a part of a cyber espionage marketing campaign set in opposition to the backdrop of the continued Russo-Ukrainian battle.
MotW is a safety characteristic carried out by Microsoft in Home windows to forestall the automated execution of recordsdata downloaded from the web with out performing additional checks via 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 basis explanation for CVE-2025-0411 is that previous to model 24.09, 7-Zip didn’t correctly propagate MotW protections to the content material of double-encapsulated archives,” Girnus defined. “This enables menace actors to craft archives containing malicious scripts or executables that won’t obtain MotW protections, leaving Home windows customers weak to assaults.”
Assaults leveraging the flaw as a zero-day had 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 comprises a specially-crafted archive file that, in flip, employs a homoglyph assault to go off the inside ZIP archive as a Microsoft Phrase doc file, successfully triggering the vulnerability.
The phishing messages, per Pattern Micro, had 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 usage of these compromised e mail accounts lend an air of authenticity to the emails despatched to targets, manipulating potential victims into trusting the content material and their senders,” Girnus identified.
This strategy 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 comprises the SmokeLoader executable that is disguised as a PDF doc.
A minimum of 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 attention-grabbing takeaway we seen within the organizations focused and affected on this marketing campaign is smaller native authorities our bodies,” Girnus mentioned.
“These organizations are sometimes underneath intense cyber stress but are sometimes missed, much less cyber-savvy, and lack the assets for a complete cyber technique that bigger authorities organizations have. These smaller organizations might be useful pivot factors by menace actors to pivot to bigger authorities organizations.”