Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Risk

6/16/2008
11:14 PM
George V. Hulme
George V. Hulme
Commentary
50%
50%

Antivirus Firm: Use File Recovery Tools To Defeat Ransomware Attack

While Kaspersky Lab says it's currently not possible to decrypt files encrypted by the most recent variant of the so-called "ransomware" Gpcode virus, file recovery tools just might get your data back.

While Kaspersky Lab says it's currently not possible to decrypt files encrypted by the most recent variant of the so-called "ransomware" Gpcode virus, file recovery tools just might get your data back.Most readers of InformationWeek are probably aware that deleted files aren't really deleted. When you hit the delete key, the space used by the file is marked as writable, and the "deleted" file exists until either overwritten through normal system use, or forensically wiped by special software. Wiping tools overwrite files a certain number of times until file recovery is virtually impossible. (I know: there are theoretical ways to potentially recover files using electronic wave-algorithm voodoo and an electron microscope. But unless you are NASA or the NSA, you don't have these resources, or the skills.)

This means that those infected by Gpcode, which we covered last week, and have their files encrypted and are then asked to pay a ransom for the decryption key, can try to use file recovery software in an attempt to get their data back.

The most recent update of the Kaspersky Gpcode.ak advisory suggests using a program, PhotoRec, to "recover your original files which were deleted by Gpcode after the virus created an encrypted version of the files."

I've no experience with PhotoRec, and I imagine many file recovery tools could get the job done. The trick is to write as little as possible to the hard-drive where the deleted files reside.

It doesn't appear that Gpcode overwrites the clear-text files before they're scrambled, not even once, after it runs its encryption scheme. While this step would render recovery software near useless, it would also be time consuming, and most users would notice the hit on their system performance during the process. Not a desirable condition for a successful attack.

Instead, the virus writers are relying on users' ignorance that they may actually be able to recover the unencrypted, and deleted versions, of the encrypted files.

If you happen to be one of the relatively few and unfortunate to have been nailed by Gpcode, using recovery software would probably be your best shot at recovering your files. Unless the Gpcode authors have some type of error in their use of the encryption (which happens to be Microsoft Enhanced Cryptographic Provider v1.0 and built into the OS) no one is cracking the RSA 1024-bit key. Not in this decade.

However, something all of us should do regularly also would be the best file-recovery solution available. At his blog, Bruce Schneier makes the great point: regular use of backup software is essential security:

The single most important thing any company or individual can do to improve security is have a good backup strategy. It's been true for decades, and it's still true today.

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
COVID-19: Latest Security News & Commentary
Dark Reading Staff 9/25/2020
9 Tips to Prepare for the Future of Cloud & Network Security
Kelly Sheridan, Staff Editor, Dark Reading,  9/28/2020
Malware Attacks Declined But Became More Evasive in Q2
Jai Vijayan, Contributing Writer,  9/24/2020
Register for Dark Reading Newsletters
White Papers
Video
Cartoon
Current Issue
Special Report: Computing's New Normal
This special report examines how IT security organizations have adapted to the "new normal" of computing and what the long-term effects will be. Read it and get a unique set of perspectives on issues ranging from new threats & vulnerabilities as a result of remote working to how enterprise security strategy will be affected long term.
Flash Poll
How IT Security Organizations are Attacking the Cybersecurity Problem
How IT Security Organizations are Attacking the Cybersecurity Problem
The COVID-19 pandemic turned the world -- and enterprise computing -- on end. Here's a look at how cybersecurity teams are retrenching their defense strategies, rebuilding their teams, and selecting new technologies to stop the oncoming rise of online attacks.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2020-15216
PUBLISHED: 2020-09-29
In goxmldsig (XML Digital Signatures implemented in pure Go) before version 1.1.0, with a carefully crafted XML file, an attacker can completely bypass signature validation and pass off an altered file as a signed one. A patch is available, all users of goxmldsig should upgrade to at least revisio...
CVE-2020-4607
PUBLISHED: 2020-09-29
IBM Security Secret Server (IBM Security Verify Privilege Vault Remote 1.2 ) could allow a local user to bypass security restrictions due to improper input validation. IBM X-Force ID: 184884.
CVE-2020-24565
PUBLISHED: 2020-09-29
An out-of-bounds read information disclosure vulnerabilities in Trend Micro Apex One may allow a local attacker to disclose sensitive information to an unprivileged account on vulnerable installations of the product. An attacker must first obtain the ability to execute low-privileged code on the ...
CVE-2020-25770
PUBLISHED: 2020-09-29
An out-of-bounds read information disclosure vulnerabilities in Trend Micro Apex One may allow a local attacker to disclose sensitive information to an unprivileged account on vulnerable installations of the product. An attacker must first obtain the ability to execute low-privileged code on the ...
CVE-2020-25771
PUBLISHED: 2020-09-29
An out-of-bounds read information disclosure vulnerabilities in Trend Micro Apex One may allow a local attacker to disclose sensitive information to an unprivileged account on vulnerable installations of the product. An attacker must first obtain the ability to execute low-privileged code on the ...