Impact
An attacker could crash PocketMine-MP by sending malformed JSON in LoginPacket.
netresearch/jsonmapper allows objects to be hydrated from scalar types in JSON. However, due to the lack of validation in the code for this feature, it may output improperly initialized objects if applied to objects whose constructors don't handle the input values.
Code handling these objects in PocketMine-MP could then crash due to @required properties not being set within the objects.
In addition, because JsonMapper does not respect bStrictObjectTypes when processing arrays, it's not possible to avoid the issue by disabling the feature.
Due to the relatively high number of security issues arising from unexpected behaviour in JsonMapper, the team is exploring options to replace it.
Patches
In the meantime, the issue was fixed by pmmp/netresearch-jsonmapper@b96a209 and 6872661fd03649cc7a8762c41c16e9ee5a4de1c9.
Workarounds
Detecting the malicious data that triggers this issue is of rather high difficulty, so it's not likely that a plugin would be able to easily remediate this.
References
cweiske/jsonmapper#225
cweiske/jsonmapper#226
References
dktapps Remediation developer
MrDiamond64 Reporter
Impact
An attacker could crash PocketMine-MP by sending malformed JSON in LoginPacket.
netresearch/jsonmapper allows objects to be hydrated from scalar types in JSON. However, due to the lack of validation in the code for this feature, it may output improperly initialized objects if applied to objects whose constructors don't handle the input values.
Code handling these objects in PocketMine-MP could then crash due to
@requiredproperties not being set within the objects.In addition, because JsonMapper does not respect
bStrictObjectTypeswhen processing arrays, it's not possible to avoid the issue by disabling the feature.Due to the relatively high number of security issues arising from unexpected behaviour in JsonMapper, the team is exploring options to replace it.
Patches
In the meantime, the issue was fixed by pmmp/netresearch-jsonmapper@b96a209 and 6872661fd03649cc7a8762c41c16e9ee5a4de1c9.
Workarounds
Detecting the malicious data that triggers this issue is of rather high difficulty, so it's not likely that a plugin would be able to easily remediate this.
References
cweiske/jsonmapper#225
cweiske/jsonmapper#226
References