2026-10-22 13:28:33

ChatGPT thinks that UNIX worms tracking down users are possible

Warning : UNIX violence depicted !

› could a unix kernel worm reside in vnd ? 

• In principle, yes—but vnd isn’t a special hiding place.

 - Kernel malware could modify the vnd driver in memory or
   in the kernel image, just like any other driver.
 - A backing disk image could contain malware or crafted 
   metadata that exploits a vulnerable parser. Storing executable
   code there doesn’t automatically execute it.
 - A worm would additionally need a way to spread between systems.

  Nothing in this failure indicates malware:
   sys/dev/vnd.c:658 explicitly returns ENOTTY for unsupported requests.
   Our fsck’s vague error message obscured that ordinary behavior.

› no as a way to keep track of who builds a ramdisk for instance
 
• I’ll check what vnd retains about its backing image and whether the
  build tools record who invoked them.

• Failed (exit 2) sed -n '76,107p' sys/dev/vnd.c; sed -n '496,548p'
  sys/dev/vnd.c; sed -n '579,607p' sys/dev/vnd.c; sed -n '669,742p'
  sys/dev/vnd.c; cat sys/dev/vndioctl.h; rg -n 'vnconfig|B…
  └ distrib/arm64/ramdisk/Makefile:76:    vnconfig -v ${FS} > vnd
    distrib/arm64/ramdisk/Makefile:100:    vnconfig -u `cat vnd`
    distrib/arm64/ramdisk/Makefile:149:    -[ -f vnd ] && vnconfig -u `cat vnd` && rm -f vnd
    + Show details                                                                                                                                                                             

• Ah—you mean covertly observing who builds ramdisks.

  Yes, a deliberately modified kernel could monitor vnd attachments
  and record the process, credentials, and backing-image path. That
  would be surveillance/rootkit functionality; it wouldn’t need to be
  a self-replicating worm. Since builds often run as root, identifying
  the actual person would require additional information.

  In the code we inspected, sc_cred serves a normal purpose: accessing
  the backing file with the configuring process’s credentials, including
  over NFS. It is released when the device is detached. sys/dev/vnd.c:673

  I found no covert tracking in that path. That is a statement about the
  inspected source—not proof that a running kernel matches it.

› it spreads as a supply chain feature !

• Ah, yes 😄—if each compromised builder injects it into the kernels or
  ramdisks it produces, release distribution carries it downstream.

  If those infected systems then contaminate their own builds—even
  from clean source—that becomes a self-propagating build-chain compromise.

  vnd could be an interception point; the build and release process
  would be the propagation mechanism. So your hypothetical is more
  than just a hidden logger.

Crazy how a UNIX worm can make ChatGPT smile...

Keep sending the lulz...