Why does avast find stuff in boot-time scan which it didnt find in normal scan?

DaRuSsIaMaN · 21-06-2006, 06:26 AM

Umm yeah, not much else to say. It found like 3 trojans after not finding anything in a normal scan just a day or less b4 that. So why's boot-time scan more perceptive?

thomas234 · 21-06-2006, 08:19 PM

The only possible thing I can think of is when your computer starts Windows/Linux, the trojan in the background stops your computer detecting it, whereas at a boot scan, the trojan hasn't started up, and therefore cannot stop avast finding it. I'm probably wrong, but it's the only possible explanation I can think of.

megamaced · 22-06-2006, 12:55 AM

Yes it's possible that the virus could operate in a kind of stealth mode. A boot time scan prevents other services from running, hence the virus is not active at this time either and not able to hide itself.

Thanks for pointing this out

Anti-Trend · 22-06-2006, 04:00 AM

A rootkit can alter the results of a scan. Pre-boot scans have the benefit of running before the rest of the system has loaded.

BTW, The boot-time scan only applies to Windows unless you're booting from a bootdisk. If you're multi-booting with Linux, it's extremely probable that only Windows was effected.

21-06-2006, 06:26 AM	#1 (permalink) Top
DaRuSsIaMaN Geek Comrade Join Date: Nov 2003 Age: 22 Male Posts: 749 Times Helpful: 12 Status: Offline My Computer	Why does avast find stuff in boot-time scan which it didnt find in normal scan? Umm yeah, not much else to say. It found like 3 trojans after not finding anything in a normal scan just a day or less b4 that. So why's boot-time scan more perceptive? __________________ Ignorance is bliss. Oedipus ruined a great sex life by asking too many questions... "So, got any kids?" - Stephen Colbert My computer is not much to brag about, but I shall do so anyway. AMD 1800+ Athlon XP..............SoundBlaster PCI 512 ASUS A7N8X..........................WD 80GB ATI Radeon 8500....................WinXP Pro

21-06-2006, 08:19 PM	#2 (permalink) Top
thomas234 Big Geek Join Date: Feb 2006 Age: 16 Male Posts: 753 Times Helpful: 33 My Mood: Bored Status: Offline My Computer	The only possible thing I can think of is when your computer starts Windows/Linux, the trojan in the background stops your computer detecting it, whereas at a boot scan, the trojan hasn't started up, and therefore cannot stop avast finding it. I'm probably wrong, but it's the only possible explanation I can think of. __________________ Nikon D40 + Sigma 18-200 f/3.5-6.3 + Nikon Speedlight SB-600 Nokia N95 & 8gb card

22-06-2006, 12:55 AM	#3 (permalink) Top
megamaced Geek Geek Geek! Join Date: Nov 2005 Age: 24 Male Posts: 3,466 Times Helpful: 352 My Mood: Fine Status: Online My Computer	Yes it's possible that the virus could operate in a kind of stealth mode. A boot time scan prevents other services from running, hence the virus is not active at this time either and not able to hide itself. Thanks for pointing this out __________________ "A computer is like air conditioning: it becomes useless when you open windows". ~Linus Torvalds

22-06-2006, 04:00 AM	#4 (permalink) Top
Anti-Trend Nonconformist Geek Join Date: Oct 2003 Age: 27 Male Posts: 4,879 Times Helpful: 535 Status: Offline My Computer	A rootkit can alter the results of a scan. Pre-boot scans have the benefit of running before the rest of the system has loaded. BTW, The boot-time scan only applies to Windows unless you're booting from a bootdisk. If you're multi-booting with Linux, it's extremely probable that only Windows was effected. __________________ See My Desktop \| Try Linux \| Install Linux \| Visit My Server \| Support Hardware Forums \| Easily rip DVDs in Linux \| Remember Everything

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