malicious software malicious software han zhang & ruochen sun
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Malicious SoftwareMalicious Software
Han Zhang & Ruochen SunHan Zhang & Ruochen Sun
Malicious SoftwareMalicious Software
http://www.youtube.com/watch?http://www.youtube.com/watch?v=uvEz8dNilvo&feature=channel_video_titv=uvEz8dNilvo&feature=channel_video_titlele
Backdoor or TrapdoorBackdoor or Trapdoor
secret entry point into a programsecret entry point into a program allows those who know access bypassing allows those who know access bypassing
usual security proceduresusual security procedures have been commonly used by developershave been commonly used by developers a threat when left in production programs a threat when left in production programs
allowing exploited by attackersallowing exploited by attackers requires good s/w development & updaterequires good s/w development & update
Logic BombLogic Bomb
one of oldest types of malicious softwareone of oldest types of malicious software code embedded in legitimate programcode embedded in legitimate program activated when specified conditions metactivated when specified conditions met
eg presence/absence of some fileeg presence/absence of some file particular date/timeparticular date/time particular userparticular user
when triggered typically damage systemwhen triggered typically damage system modify/delete files/disks, halt machine, etcmodify/delete files/disks, halt machine, etc
Trojan HorseTrojan Horse
program with hidden side-effects program with hidden side-effects which is usually superficially attractivewhich is usually superficially attractive
eg game, s/w upgrade etc eg game, s/w upgrade etc when run performs some additional taskswhen run performs some additional tasks
allows attacker to indirectly gain access they do not allows attacker to indirectly gain access they do not have directlyhave directly
often used to propagate a virus/worm or install a often used to propagate a virus/worm or install a backdoorbackdoor
or simply to destroy dataor simply to destroy data
Mobile CodeMobile Code
program/script/macro that runs unchangedprogram/script/macro that runs unchanged on heterogeneous collection of platformson heterogeneous collection of platforms on large homogeneous collection (Windows)on large homogeneous collection (Windows)
transmitted from remote system to local transmitted from remote system to local system & then executed on local systemsystem & then executed on local system
often to inject virus, worm, or Trojan horseoften to inject virus, worm, or Trojan horse or to perform own exploitsor to perform own exploits
unauthorized data access, root compromiseunauthorized data access, root compromise
Multiple-Threat MalwareMultiple-Threat Malware malware may operate in multiple waysmalware may operate in multiple ways multipartite multipartite virus infects in multiple waysvirus infects in multiple ways
eg. multiple file typeseg. multiple file types blended blended attack uses multiple methods of attack uses multiple methods of
infection or transmissioninfection or transmission to maximize speed of contagion and severityto maximize speed of contagion and severity may include multiple types of malwaremay include multiple types of malware eg. Nimda has worm, virus, mobile codeeg. Nimda has worm, virus, mobile code can also use IM & P2Pcan also use IM & P2P
VirusesViruses
piece of software that infects programspiece of software that infects programs modifying them to include a copy of the virusmodifying them to include a copy of the virus so it executes secretly when host program is runso it executes secretly when host program is run
specific to operating system and hardwarespecific to operating system and hardware taking advantage of their details and weaknessestaking advantage of their details and weaknesses
a typical virus goes through phases of:a typical virus goes through phases of: dormantdormant propagationpropagation triggeringtriggering executionexecution
Virus StructureVirus Structure
components:components: infection mechanism - enables replicationinfection mechanism - enables replication trigger - event that makes payload activatetrigger - event that makes payload activate payload - what it does, malicious or benignpayload - what it does, malicious or benign
prepended / postpended / embedded prepended / postpended / embedded when infected program invoked, executes when infected program invoked, executes
virus code then original program codevirus code then original program code can block initial infection (difficult)can block initial infection (difficult) or propogation (with access controls)or propogation (with access controls)
Virus StructureVirus Structure
Compression VirusCompression Virus
Virus ClassificationVirus Classification
boot sectorboot sector file infectorfile infector macro virusmacro virus encrypted virusencrypted virus stealth virusstealth virus polymorphic viruspolymorphic virus metamorphic virusmetamorphic virus
Macro VirusMacro Virus
became very common in mid-1990s sincebecame very common in mid-1990s since platform independentplatform independent infect documentsinfect documents easily spreadeasily spread
exploit macro capability of office appsexploit macro capability of office apps executable program embedded in office docexecutable program embedded in office doc often a form of Basicoften a form of Basic
more recent releases include protectionmore recent releases include protection recognized by many anti-virus programsrecognized by many anti-virus programs
E-Mail VirusesE-Mail Viruses
more recent developmentmore recent development e.g. Melissae.g. Melissa
exploits MS Word macro in attached docexploits MS Word macro in attached doc if attachment opened, macro activatesif attachment opened, macro activates sends email to all on users address listsends email to all on users address list and does local damageand does local damage
then saw versions triggered reading emailthen saw versions triggered reading email hence much faster propagationhence much faster propagation
Virus CountermeasuresVirus Countermeasures
prevention - ideal solution but difficultprevention - ideal solution but difficult realistically need:realistically need:
detectiondetection identificationidentification removalremoval
if detect but can’t identify or remove, must if detect but can’t identify or remove, must discard and replace infected programdiscard and replace infected program
Anti-Virus EvolutionAnti-Virus Evolution
virus & antivirus tech have both evolvedvirus & antivirus tech have both evolved early viruses simple code, easily removedearly viruses simple code, easily removed as become more complex, so must the as become more complex, so must the
countermeasurescountermeasures generationsgenerations
first - signature scannersfirst - signature scanners second - heuristicssecond - heuristics third - identify actionsthird - identify actions fourth - combination packagesfourth - combination packages
Generic DecryptionGeneric Decryption
runs executable files through GD scanner:runs executable files through GD scanner: CPU emulator to interpret instructionsCPU emulator to interpret instructions virus scanner to check known virus signaturesvirus scanner to check known virus signatures emulation control module to manage processemulation control module to manage process
lets virus decrypt itself in interpreterlets virus decrypt itself in interpreter periodically scan for virus signaturesperiodically scan for virus signatures issue is long to interpret and scanissue is long to interpret and scan
tradeoff chance of detection vs time delaytradeoff chance of detection vs time delay
Digital Immune SystemDigital Immune System
Behavior-Blocking SoftwareBehavior-Blocking Software
WormsWorms
replicating program that propagates over netreplicating program that propagates over net using email, remote exec, remote login using email, remote exec, remote login
has phases like a virus:has phases like a virus: dormant, propagation, triggering, executiondormant, propagation, triggering, execution propagation phase: searches for other systems, propagation phase: searches for other systems,
connects to it, copies self to it and runsconnects to it, copies self to it and runs
may disguise itself as a system processmay disguise itself as a system process concept seen in Brunner’s “Shockwave Rider”concept seen in Brunner’s “Shockwave Rider” implemented by Xerox Palo Alto labs in 1980’simplemented by Xerox Palo Alto labs in 1980’s
Morris WormMorris Worm
one of best know wormsone of best know worms released by Robert Morris in 1988released by Robert Morris in 1988 various attacks on UNIX systemsvarious attacks on UNIX systems
cracking password file to use login/password cracking password file to use login/password to logon to other systemsto logon to other systems
exploiting a bug in the finger protocolexploiting a bug in the finger protocol exploiting a bug in sendmailexploiting a bug in sendmail
if succeed have remote shell accessif succeed have remote shell access sent bootstrap program to copy worm oversent bootstrap program to copy worm over
Worm Propagation ModelWorm Propagation Model
Recent Worm AttacksRecent Worm Attacks Code RedCode Red
July 2001 exploiting MS IIS bugJuly 2001 exploiting MS IIS bug probes random IP address, does DDoS attackprobes random IP address, does DDoS attack
Code Red II variant includes backdoorCode Red II variant includes backdoor SQL SlammerSQL Slammer
early 2003, attacks MS SQL Serverearly 2003, attacks MS SQL Server MydoomMydoom
mass-mailing e-mail worm that appeared in 2004mass-mailing e-mail worm that appeared in 2004 installed remote access backdoor in infected systemsinstalled remote access backdoor in infected systems
Warezov family of wormsWarezov family of worms scan for e-mail addresses, send in attachmentscan for e-mail addresses, send in attachment
Worm TechnologyWorm Technology
multiplatformmultiplatform multi-exploitmulti-exploit ultrafast spreadingultrafast spreading polymorphicpolymorphic metamorphicmetamorphic transport vehiclestransport vehicles zero-day exploit zero-day exploit
Mobile Phone WormsMobile Phone Worms
first appeared on mobile phones in 2004first appeared on mobile phones in 2004 target smartphone which can install s/wtarget smartphone which can install s/w
they communicate via Bluetooth or MMSthey communicate via Bluetooth or MMS to disable phone, delete data on phone, or to disable phone, delete data on phone, or
send premium-priced messagessend premium-priced messages CommWarrior, launched in 2005CommWarrior, launched in 2005
replicates using Bluetooth to nearby phonesreplicates using Bluetooth to nearby phones and via MMS using address-book numbersand via MMS using address-book numbers
Worm CountermeasuresWorm Countermeasures
overlaps with anti-virus techniquesoverlaps with anti-virus techniques once worm on system A/V can detectonce worm on system A/V can detect worms also cause significant net activityworms also cause significant net activity worm defense approaches include:worm defense approaches include:
signature-based worm scan filteringsignature-based worm scan filtering filter-based worm containmentfilter-based worm containment payload-classification-based worm containmentpayload-classification-based worm containment threshold random walk scan detectionthreshold random walk scan detection rate limiting and rate haltingrate limiting and rate halting
Proactive Worm ContainmentProactive Worm Containment
Network Based Worm DefenseNetwork Based Worm Defense
THANK YOU!THANK YOU!
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