Malicious Automated Software Update
Attack Pattern ID: 187 (Standard Attack Pattern Completeness: Complete)Typical Severity: HighStatus: Draft
+ Description


An attacker exploits a weakness in a server or client's process of delivering and verifying the integrity of code supplied by an update-providing server or mechanism to cause code of the attacker's choosing to be downloaded and installed as a software update. Attacks against automated update mechanisms involve attack vectors which are specific to the type of update mechanism, but typically involve two different attack strategies: redirection or spoofing. Redirection-based attacks exploit two layers of weaknesses in server or client software to undermine the integrity of the target code-base.

The first weakness involves a failure to properly authenticate a server as a source of update or patch content. This type of weakness typically results from authentication mechanisms which can be defeated, allowing a hostile server to satisfy the criteria that establish a trust relationship. The second weakness is a systemic failure to validate the identity and integrity of code downloaded from a remote location, hence the inability to distinguish malicious code from a legitimate update.

One predominate type of redirection attack requires DNS spoofing or hijacking of a domain name corresponding to an update server. The target software initiates an update request and the DNS request resolves the domain name of the update server to the IP address of the attacker, at which point the software accepts updates either transmitted by or pulled from the attacker's server. Attacks against DNS mechanisms comprise an initial phase of a chain of attacks that facilitate automated update hijacking attack, and such attacks have a precedent in targeted activities that have been as complex as DNS/BIND attacks of corporate infrastructures, to untargeted attacks aimed at compromising home broadband routers, as well as attacks involving the compromise of wireless access points, as well as 'evil twin' attacks coupled with DNS redirection. Due to the plethora of options open to the attacker in forcing name resolution to arbitrary servers the Automated Update Hijacking attack strategies are the tip of the spear for many multi-stage attack chains.

The second weakness that is exploited by the attacker is the lack of integrity checking by the software in validating the update. Software which relies only upon domain name resolution to establish the identity of update code is particularly vulnerable, because this signals an absence of other security countermeasures that could be applied to invalidate the attacker's payload on basis of code identity, hashing, signing, encryption, and other integrity checking mechanisms. Redirection-based attack patterns work equally well against client-side software as well as local servers or daemons that provide software update functionality. One precedent of redirection-based attacks involves the active exploitation of Firefox extensions, such as the Google Toolbar, Yahoo Toolbar, Facebook Toolbar, and others.

The second strategy employed in Automated Hijacking Attacks are spoofing strategies, including content or identity spoofing, as well as protocol spoofing. Content or identity spoofing attacks can trigger updates in software by embedding scripted mechanisms within a malicious web page, which masquerades as a legitimate update source. Scripting mechanisms communicate with software components and trigger updates from locations specified by the attacker's server. Such attacks have numerous precedents, one in particular being eTrust Antivirus Webscan Automated Update Remote Code Execution vulnerability (CVE-2006-3976) and (CVE-2006-3977) whereby an ActiveX control could be remotely manipulated by an attacker controlled web page to download and execute the attacker's code without integrity checking.

+ Related Weaknesses
CWE-IDWeakness NameWeakness Relationship Type
494Download of Code Without Integrity CheckTargeted
+ Related Attack Patterns
NatureTypeIDNameDescriptionView(s) this relationship pertains toView\(s\)
ChildOfAttack PatternAttack Pattern105HTTP Request Splitting 
Mechanism of Attack (primary)1000
ChildOfAttack PatternAttack Pattern186Malicious Software Update 
Mechanism of Attack1000