Security experts are warning of a variation on the classic ransomware attack in which cyber-criminals compromise a victim company’s web app before encrypting and holding the related database to ransom.
The technique was first spotted in December last year by Swiss security vendor High-Tech Bridge, which dubbed it 'RansomWeb'.
It reported that cyber-criminals first look to compromise a web app by modifying several scripts. These effectively patch the system on the fly, encrypting data before it’s stored in the relevant database and decrypting it when it is read.
This all happens without the knowledge of the targeted company, as the patch doesn’t affect the website because only the critical fields of the database are encrypted, the firm said in a blog post.
The vital encryption key is stored on a remote web server only accessible via HTTPS.
“During six months, hackers were silently waiting, while backups were being overwritten by the recent versions of the database,” the firm continued.
“At the day X, hackers removed the key from the remote server. Database became unusable, website went out of service, and hackers demanded a ransom for the encryption key.”
That particular attack was aimed at a financial company, but High-Tech Bridge has also seen it affect an SMB’s phpBB forum – which was used by the firm as its main platform for customer support.
The security vendor warned that this attack method could ensure denial of service on a mission critical web app more effectively than a DDoS. Back-ups won’t help and it’s almost impossible, once infected, to recover without paying the ransom.
However, file integrity monitoring tools might at least give firms greater visibility into whether they’ve been infected, before back-ups become useless, the vendor claimed.
High-Tech Bridge CEO, Ilia Kolochenko, said it was unclear if the more targeted RansomWeb attacks will become favored over traditional ransomware campaigns.
“However, RansomWeb attacks may grow significantly as very few people and companies pay necessary attention to their website security,” he told Infosecurity. “And hackers adore easy targets for mass compromises.”