Home > CAPEC List > CAPEC-67: String Format Overflow in syslog() (Version 3.0)  

CAPEC-67: String Format Overflow in syslog()

Attack Pattern ID: 67
Abstraction: Detailed
Status: Draft
Presentation Filter:
+ Description
This attack targets the format string vulnerabilities in the syslog() function. An attacker would typically inject malicious input in the format string parameter of the syslog function. This is a common problem, and many public vulnerabilities and associated exploits have been posted.
+ Likelihood Of Attack

High

+ Typical Severity

Very High

+ Relationships

The table(s) below shows the other attack patterns and high level categories that are related to this attack pattern. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as CanFollow, PeerOf, and CanAlsoBe are defined to show similar attack patterns that the user may want to explore.

+ Relevant to the view "Mechanisms of Attack" (CAPEC-1000)
NatureTypeIDName
ChildOfStandard Attack PatternStandard Attack Pattern - A standard level attack pattern in CAPEC is focused on a specific methodology or technique used in an attack. It is often seen as a singular piece of a fully executed attack. A standard attack pattern is meant to provide sufficient details to understand the specific technique and how it attempts to accomplish a desired goal. A standard level attack pattern is a specific type of a more abstract meta level attack pattern.100Overflow Buffers
CanFollowStandard Attack PatternStandard Attack Pattern - A standard level attack pattern in CAPEC is focused on a specific methodology or technique used in an attack. It is often seen as a singular piece of a fully executed attack. A standard attack pattern is meant to provide sufficient details to understand the specific technique and how it attempts to accomplish a desired goal. A standard level attack pattern is a specific type of a more abstract meta level attack pattern.69Target Programs with Elevated Privileges
+ Execution Flow
Explore
  1. The attacker finds that he can inject data to the format string parameter of Syslog().

Exploit
  1. The attacker craft a malicious input and inject it into the format string parameter. From now on, the attacker can execute arbitrary code and do more damage.

+ Prerequisites
The format string argument of the Syslog function can be tainted with user supplied data.
+ Consequences

The table below specifies different individual consequences associated with the attack pattern. The Scope identifies the security property that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in their attack. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a pattern will be used to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.

ScopeImpactLikelihood
Confidentiality
Integrity
Availability
Execute Unauthorized Commands
Availability
Unreliable Execution
Confidentiality
Access Control
Authorization
Gain Privileges
Integrity
Modify Data
+ Mitigations

The code should be reviewed for misuse of the Syslog function call. Manual or automated code review can be used. The reviewer needs to ensure that all format string functions are passed a static string which cannot be controlled by the user and that the proper number of arguments are always sent to that function as well. If at all possible, do not use the %n operator in format strings. The following code shows a correct usage of Syslog():

syslog(LOG_ERR, "%s", cmdBuf);

The following code shows a vulnerable usage of Syslog():

syslog(LOG_ERR, cmdBuf);
// the buffer cmdBuff is taking user supplied data.
+ Example Instances
Format string vulnerability in TraceEvent function for ntop before 2.1 allows remote attackers to execute arbitrary code by causing format strings to be injected into calls to the syslog function, via (1) an HTTP GET request, (2) a user name in HTTP authentication, or (3) a password in HTTP authentication. See also: CVE-2002-0412
+ Memberships
This MemberOf Relationships table shows additional CAPEC Categories and Views that reference this attack pattern as a member. This information is often useful in understanding where a attack pattern fits within the context of external information sources.
NatureTypeIDName
MemberOfCategoryCategory - A category in CAPEC is a collection of attack patterns based on some common characteristic. More specifically, it is an aggregation of attack patterns based on effect/intent (as opposed to actions or mechanisms, such an aggregation would be a meta attack pattern). An aggregation based on effect/intent is not an actionable attack and as such is not a pattern of attack behavior. Rather, it is a grouping of patterns based on some common criteria.339WASC-06 - Format String
+ References
[REF-1] G. Hoglund and G. McGraw. "Exploiting Software: How to Break Code". Addison-Wesley. 2004-02.
[REF-503] scut and team teso. "Exploiting Format String Vulnerabilities". <http://doc.bughunter.net/format-string/exploit-fs.html>.
[REF-504] Halvar Flake. "Auditing binaries for security vulnerabilities". <http://www.blackhat.com/presentations/bh-europe-00/HalvarFlake/HalvarFlake.ppt>.
[REF-505] "Fortify Taxonomy of Vulnerabilities". Fortify Software. <https://vulncat.hpefod.com/en>.
[REF-506] "Syslog man page". <http://www.rt.com/man/syslog.3.html>.
+ Content History
Submissions
Submission DateSubmitterOrganization
2014-06-23CAPEC Content TeamThe MITRE Corporation
Modifications
Modification DateModifierOrganization
2017-01-09CAPEC Content TeamThe MITRE Corporation
Updated Related_Attack_Patterns
2018-07-31CAPEC Content TeamThe MITRE Corporation
Updated References

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Page Last Updated or Reviewed: July 31, 2018