by Greg Smith
Mobile Telephone Evidence & Forensics
trewmte.blogspot.com

I have discovered that it is possible when manually examining some SonyEricssons (such as "K" range etc) that after a user has deleted the Last Number Dialled (LND) from the call register that it is possible to recover the last ten numbers dialled on the handset using the 'menu keys'.

Here is the routine**:

- Select Menu
- Select Messages
- Select Write New
- Select Text Message: this displays the screen to commence entering text but no need to enter any text leave screen blank
- Select Continue
- Select Addr. book look-up (can also state Contacts look-up): the screen now displays phonebook contacts
- Select More
- Select "Unsaved numbers": displays dialled numbers for LND that had been deleted

There are some noteworthy points to consider:

a) the recovered numbers cannot have already been saved into either the Phonebook of the handset or *SIM;
b) there are no dates and times when numbers were dialled;
c) the unsaved recovered numbers appear in a random order.

*Checks were also made to ensure the recovered deleted numbers were not stored in 7F10 6F44 (EFLND) in SIM.

In recovering this information I found when conducting tests using handset readers *none* detected what may amount to important evidence. Most importantly, if produced in evidence (by one party against another) that failure to detect such evidence may suggest a systemic failure of practises/practices and/or procedures regarding the examination of this make and its various models.

I do not think that the above analogy could be suggested as fair as an overall statement of affairs because:

d) the latest "w" range of SonyEricsson does not appear to have this functionality as far as I can tell, but further research is needed;
e) The English user manual for the K600i and K800i makes no mention of such a function, which I am describing as 'recovery of data that may have evidential value arising from an undocumented functionality of a particular handset'. Thus, this matter needs to be considered on a case by case (model by model) approach.

Ultimately this finding underpins the principle that examiners cannot solely rely and transfer their responsibility onto so called 'forensic devices' to produce reliable findings, that human intervention is paramount when dealing with mobile telephone examination and evidence. My observations therefore do not rule out using forensic devices or software device readers that are used to recover data that are commonly served in evidence. The objective of raising this matter is one of awareness and that the skillsets required for manual examination must be retained.

**Note: I have been informed that the above routine doesn't work on the SonyEricsson K850.

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