[News] Microsoft Office Built-In Feature Could be Exploited to Create Self-Replicating Malware
[News]
Microsoft Office Built-In Feature Could be Exploited to Create Self-Replicating Malware
An Italian researcher from the security firm InTheCyber devised an attack technique to create self-replicating malware hidden in MS Word documents.
Earlier this month a cybersecurity researcher shared details of a security loophole with The Hacker News that affects all versions of Microsoft Office, allowing malicious actors to create and spread macro-based self-replicating malware.
Lino Antonio Buono, an Italian security researcher who works at InTheCyber, reported a simple technique (detailed below) that could allow anyone to bypass the security control put in place by Microsoft and create self-replicating malware hidden behind innocent-looking Microsoft Word documents.
What's Worse? Microsoft refused to consider this issue a security loophole when contacted by the researcher in October this year, saying it's a feature intended to work this way only—just like Microsoft Office DDE feature, which is now actively being used by hackers.
Macro-based self-replicating malware, which basically allows a macro to write more macros, is not new among hackers, but to prevent such threats, Microsoft has already introduced a security mechanism in Microsoft Office that by default limits this functionality.
The qkG ransomware employs Auto Close VBA macro—a technique that allows executing malicious macro when victim closes the document.
Although the first variant of the qkG ransomware did include a Bitcoin address, the latest sample analyzed by Trend Micro includes it and demands $300 in BTC.
Experts observed that the Bitcoin address hasn’t received any payment yet, a circumstance that suggest crooks still haven’t spread it in the wild.
Moreover, this ransomware is currently using the same hard-coded password: "I’m QkG@PTM17! by TNA@MHT-TT2" that unlocks affected files.
Here's How this New Attack Technique Works
Microsoft has untrusted external macros by default and to restrict default programmatic access to Office VBA project object model. Users can manually enable “Trust access to the VBA project object model,” if required.
In other words, if the victim mistakenly allows the malicious doc file to run macros once, his/her system would remain open to macro-based attacks.
Moreover, the victim will also be unknowingly responsible for spreading the same malicious code to other users by sharing any infected office files from his/her system.
This attack technique could be more worrisome when you receive a malicious doc file from a trusted contact who have already been infected with such malware, eventually turning you into its next attack vector for others.
Although this technique is not being exploited in the wild, the researcher believes it could be exploited to spread dangerous self-replicating malware that could be difficult to deal with and put an end.
Since this is a legitimate feature, most antivirus solutions do not flag any warning or block MS Office documents with VBA code, neither the tech company has any plans of issuing a patch that would restrict this functionality.
"In order to (partially) mitigate the vulnerability it is possible to move the AccessVBOM registry key from the HKCU hive to the HKLM, making it editable only by the system administrator." - Buono said -
The best way to protect yourself from such malware is always to be suspicious of any uninvited documents sent via an email and never click on links inside those documents unless adequately verifying the source.
Microsoft Office Built-In Feature Could be Exploited to Create Self-Replicating Malware
An Italian researcher from the security firm InTheCyber devised an attack technique to create self-replicating malware hidden in MS Word documents.
Earlier this month a cybersecurity researcher shared details of a security loophole with The Hacker News that affects all versions of Microsoft Office, allowing malicious actors to create and spread macro-based self-replicating malware.
Lino Antonio Buono, an Italian security researcher who works at InTheCyber, reported a simple technique (detailed below) that could allow anyone to bypass the security control put in place by Microsoft and create self-replicating malware hidden behind innocent-looking Microsoft Word documents.
What's Worse? Microsoft refused to consider this issue a security loophole when contacted by the researcher in October this year, saying it's a feature intended to work this way only—just like Microsoft Office DDE feature, which is now actively being used by hackers.
Macro-based self-replicating malware, which basically allows a macro to write more macros, is not new among hackers, but to prevent such threats, Microsoft has already introduced a security mechanism in Microsoft Office that by default limits this functionality.
New 'qkG Ransomware' Found Using Same Self-Spreading Technique
Trend Micro published a report on a new piece of macro-based self-replicating ransomware, dubbed "qkG," which exploits exactly the same Microsoft Office feature.
It’s also one of the few that uncommonly employs malicious macro codes, unlike the usual families that use macros mainly to download the ransomware.
The qkG ransomware employs Auto Close VBA macro—a technique that allows executing malicious macro when victim closes the document.
Experts observed that the Bitcoin address hasn’t received any payment yet, a circumstance that suggest crooks still haven’t spread it in the wild.
Moreover, this ransomware is currently using the same hard-coded password: "I’m QkG@PTM17! by TNA@MHT-TT2" that unlocks affected files.
Here's How this New Attack Technique Works
Buono shared a video PoC of the attack technique with colleagues at The Hacker News. The video shows how an MS Word document embedding malicious VBA code could be used to deliver a self-replicating multi-stage malware.
Once the “Trust access to the VBA project object model” setting is enabled, Microsoft Office trusts all macros and automatically runs any code without showing any security warning or requiring user’s permission.
With "Trust access to the VBA project object model" setting enabled, Microsoft Office trusts all macros and automatically runs any code without showing security warning or requiring user's permission.
Buono found that this setting can be enabled/disabled just by editing a Windows registry, eventually enabling the macros to write more macros without user's consent and knowledge.
Buono found that this setting can be enabled/disabled just by editing a Windows registry, eventually enabling the macros to write more macros without user's consent and knowledge.
As shown in the video, a malicious Microsoft Doc file created by Buono does the same—it first edits the Windows registry and then injects same macro payload (VBA code) into every doc file that the victim creates, edits or just opens on his/her system.
Victims Will be Unknowingly Responsible for Spreading Malware Further
In other words, if the victim mistakenly allows the malicious doc file to run macros once, his/her system would remain open to macro-based attacks.
Moreover, the victim will also be unknowingly responsible for spreading the same malicious code to other users by sharing any infected office files from his/her system.
This attack technique could be more worrisome when you receive a malicious doc file from a trusted contact who have already been infected with such malware, eventually turning you into its next attack vector for others.
Although this technique is not being exploited in the wild, the researcher believes it could be exploited to spread dangerous self-replicating malware that could be difficult to deal with and put an end.
Since this is a legitimate feature, most antivirus solutions do not flag any warning or block MS Office documents with VBA code, neither the tech company has any plans of issuing a patch that would restrict this functionality.
"In order to (partially) mitigate the vulnerability it is possible to move the AccessVBOM registry key from the HKCU hive to the HKLM, making it editable only by the system administrator." - Buono said -
The best way to protect yourself from such malware is always to be suspicious of any uninvited documents sent via an email and never click on links inside those documents unless adequately verifying the source.
![[News] Microsoft Office Built-In Feature Could be Exploited to Create
Self-Replicating Malware](https://4.bp.blogspot.com/-9Obx9o8TwNM/Whbqm5pSk3I/AAAAAAAAu4w/OViwJrHylYQHwnCB975W8NLQ6ENzKi0wgCLcBGAs/s72-c/ms-office-macro-malware.png)